Trading binary options strategies and tactics torrent

Topmost binary options platform

Firebird 2.5 Language Reference,Table of Contents

Web01/11/ · Nsight Graphics™ is a standalone application for the debugging, profiling, and analysis of graphics applications. Nsight Graphics supports applications built with DirectCompute, Direct3D (11, 12), OpenGL, Vulkan, Oculus SDK, and OpenVR.. This documentation is separated up into different sections to help you understand how to get Web16/12/ · The entirety of Valve's digital games distribution platform is available on new Model S and X cars with 16GB RAM. by Ray Ampoloquio published December 15, December 15, Far Cry and Middle-Earth headline PS Plus Extra and Premium games for December Web26/10/ · Key Findings. California voters have now received their mail ballots, and the November 8 general election has entered its final stage. Amid rising prices and economic uncertainty—as well as deep partisan divisions over social and political issues—Californians are processing a great deal of information to help them choose state constitutional WebBinary Trees are the most commonly used version of trees wherein each node of the tree can have utmost two child nodes. To simplify, each node, including the root node will either have 0, 1 or 2 children, not more or less than that.. A node which has 0 children is called a leaf node. In the above figure; 4, 3, 1, 2 are the leaf nodes as they have no child nodes Web04/12/ · The Fastest Mouse Clicker for Windows wins this competition because its code is a further developing of the rest 2 popular apps. Technology. Unlike other auto-clickers that use obsolete mouse_event() system call from C/C++ source or un-arrayed SendInput() from C#/.Net source, The Fastest Mouse Clicker for Windows uses arrayed SendInput() with ... read more

For the same reasons, columns with floating-point data are not recommended for use as keys or to have uniqueness constraints applied to them. For testing data in columns with floating-point data types, expressions should check using a range, for instance, BETWEEN , rather than searching for exact matches. When using these data types in expressions, extreme care is advised regarding the rounding of evaluation results.

The FLOAT data type has an approximate precision of 7 digits after the decimal point. To ensure the safety of storage, rely on 6 digits.

The DOUBLE PRECISION data type is stored with an approximate precision of 15 digits. Fixed-point data types ensure the predictability of multiplication and division operations, making them the choice for storing monetary values. Firebird implements two fixed-point data types: NUMERIC and DECIMAL. According to the standard, both types limit the stored number to the declared scale the number of digits after the decimal point.

For instance, NUMERIC 4, 2 defines a number consisting altogether of four digits, including two digits after the decimal point; that is, it can have up to two digits before the point and no more than two digits after the point. If the number 3. The form of declaration for fixed-point data, for instance, NUMERIC p, s , is common to both types. Understanding the mechanism for storing and retrieving fixed-point data should help to visualise why: for storage, the number is multiplied by 10 s 10 to the power of s , converting it to an integer; when read, the integer is converted back.

The method of storing fixed-point data in the DBMS depends on several factors: declared precision, database dialect, declaration type. Further to the explanation above, the DBMS will store NUMERIC data according the declared precision and scale. Some more examples are:. Always keep in mind that the storage format depends on the precision.

For instance, you define the column type as NUMERIC 2,2 presuming that its range of values will be However, the actual range of values for the column will be In storage, the NUMERIC 4,2 , NUMERIC 3,2 and NUMERIC 2,2 data types are the same, in fact. It means that if you really want to store data in a column with the NUMERIC 2,2 data type and limit the range to The storage format in the database for DECIMAL is very similar to NUMERIC , with some differences that are easier to observe with the help of some more examples:.

The DATE , TIME and TIMESTAMP data types are used to work with data containing dates and times. Dialect 3 supports all the three types, while Dialect 1 has only DATE. Dialect 1 DATE data can be defined alternatively as TIMESTAMP and this is recommended for new definitions in Dialect 1 databases. If fractions of seconds are stored in date and time data types, Firebird stores them to ten-thousandths of a second.

If a lower granularity is preferred, the fraction can be specified explicitly as thousandths, hundredths or tenths of a second in Dialect 3 databases of ODS 11 or higher. The time-part of a TIME or TIMESTAMP is a 4-byte WORD, with room for decimilliseconds precision and time values are stored as the number of deci-milliseconds elapsed since midnight.

The actual precision of values stored in or read from time stamp functions and variables is:. Functions DATEADD and DATEDIFF support up to milliseconds precision. Deci-milliseconds can be specified but they are rounded to the nearest integer before any operation is performed.

For TIME and TIMESTAMP literals , Firebird happily accepts up to deci-milliseconds precision, but truncates not rounds the time part to the nearest lower or equal millisecond. Try, for example, SELECT TIME ' Deci-milliseconds precision is rare and is not currently stored in columns or variables. The best assumption to make from all this is that, although Firebird stores TIME and the TIMESTAMP time-part values as the number of deci-milliseconds 10 -4 seconds elapsed since midnight, the actual precision could vary from seconds to milliseconds.

The DATE data type in Dialect 3 stores only date without time. The available range for storing data is from January 01, 1 to December 31, In Dialect 1, date literals without a time part, as well as 'TODAY' , 'YESTERDAY' and 'TOMORROW' automatically get a zero time part. If, for some reason, it is important to you to store a Dialect 1 timestamp literal with an explicit zero time-part, the engine will accept a literal like ' However, '' would have precisely the same effect, with fewer keystrokes!

The TIME data type is available in Dialect 3 only. It stores the time of day within the range from If you need to get the time-part from DATE in Dialect 1, you can use the EXTRACT function.

See also the EXTRACT function in the chapter entitled Built-in Functions. The TIMESTAMP data type is available in Dialect 3 and Dialect 1. It is the same as the DATE type in Dialect 1. The EXTRACT function works equally well with TIMESTAMP as with the Dialect 1 DATE type. The method of storing date and time values makes it possible to involve them as operands in some arithmetic operations.

An example is to subtract an earlier date, time or timestamp from a later one, resulting in an interval of time, in days and fractions of days. DATE increased by n whole days. Broken values are rounded not floored to the nearest integer.

TIME increased by n seconds. The fractional part is taken into account. DATE reduced by n whole days. TIME reduced by n seconds. DATEADD , DATEDIFF. For working with character data, Firebird has the fixed-length CHAR and the variable-length VARCHAR data types.

The maximum size of text data stored in these data types is 32, bytes for CHAR and 32, bytes for VARCHAR. The maximum number of characters that will fit within these limits depends on the CHARACTER SET being used for the data under consideration. The collation sequence does not affect this maximum, although it may affect the maximum size of any index that involves the column. If no character set is explicitly specified when defining a character object, the default character set specified when the database was created will be used.

If the database does not have a default character set defined, the field gets the character set NONE. UTF8 comes with collations for many languages. Non-accented Latin letters occupy 1 byte, Cyrillic letters from the WIN encoding occupy 2 bytes in UTF8 , characters from other encodings may occupy up to 4 bytes.

The UTF8 character set implemented in Firebird supports the latest version of the Unicode standard, thus recommending its use for international databases. While working with strings, it is essential to keep the character set of the client connection in mind. If there is a mismatch between the character sets of the stored data and that of the client connection, the output results for string columns are automatically re-encoded, both when data are sent from the client to the server and when they are sent back from the server to the client.

The character set NONE is a special character set in Firebird. It can be characterized such that each byte is a part of a string, but the string is stored in the system without any clues about what constitutes any character: character encoding, collation, case, etc.

are simply unknown. It is the responsibility of the client application to deal with the data and provide the means to interpret the string of bytes in some way that is meaningful to the application and the human user.

Data in OCTETS encoding are treated as bytes that may not actually be interpreted as characters. OCTETS provides a way to store binary data, which could be the results of some Firebird functions. The database engine has no concept of what it is meant to do with a string of bits in OCTETS , other than just store it and retrieve it.

Again, the client side is responsible for validating the data, presenting them in formats that are meaningful to the application and its users and handling any exceptions arising from decoding and encoding them.

Each character set has a default collation sequence COLLATE that specifies the collation order. Usually, it provides nothing more than ordering based on the numeric code of the characters and a basic mapping of upper- and lower-case characters. If some behaviour is needed for strings that is not provided by the default collation sequence and a suitable alternative collation is supported for that character set, a COLLATE collation clause can be specified in the column definition.

A COLLATE collation clause can be applied in other contexts besides the column definition. If output needs to be sorted in a special alphabetic sequence, or case-insensitively, and the appropriate collation exists, then a COLLATE clause can be included with the ORDER BY clause when rows are being sorted on a character field and with the GROUP BY clause in case of grouping operations.

For a case-insensitive search, the UPPER function could be used to convert both the search argument and the searched strings to upper-case before attempting a match:. For strings in a character set that has a case-insensitive collation available, you can simply apply the collation, to compare the search argument and the searched strings directly.

The following table shows the possible collation sequences for the UTF8 character set. Collation works according to the position of the character in the table binary. Added in Firebird 2. Collation works according to the UCA algorithm Unicode Collation Algorithm alphabetical.

Case-insensitive collation, works without taking character case into account. Case-insensitive, accent-insensitive collation, works alphabetically without taking character case or accents into account. In Firebird earlier than version 2. Multi-byte character sets and compound indexes limit the size even further. The maximum length of an indexed string is 9 bytes less than that quarter-page limit.

The table below shows the maximum length of an indexed string in characters , according to page size and character set, calculated using this formula. CREATE DATABASE , Collation sequence , SELECT , WHERE , GROUP BY , ORDER BY. CHAR is a fixed-length data type. If the entered number of characters is less than the declared length, trailing spaces will be added to the field. Generally, the pad character does not have to be a space: it depends on the character set.

For example, the pad character for the OCTETS character set is zero. The full name of this data type is CHARACTER , but there is no requirement to use full names and people rarely do so. A valid length is from 1 to the maximum number of characters that can be accommodated within 32, bytes.

VARCHAR is the basic string type for storing texts of variable length, up to a maximum of 32, bytes. The stored structure is equal to the actual size of the data plus 2 bytes where the length of the data is recorded. All characters that are sent from the client application to the database are considered meaningful, including the leading and trailing spaces. However, trailing spaces are not stored: they will be restored upon retrieval, up to the recorded length of the string.

The full name of this type is CHARACTER VARYING. Another variant of the name is written as CHAR VARYING. In all other respects it is the same as CHAR. A similar data type is available for the variable-length string type: NATIONAL CHARACTER VARYING. BLOB s Binary Large Objects are complex structures used to store text and binary data of an undefined length, often very large.

Specifying the BLOB segment is throwback to times past, when applications for working with BLOB data were written in C Embedded SQL with the help of the gpre pre-compiler.

Nowadays, it is effectively irrelevant. The segment size for BLOB data is determined by the client side and is usually larger than the data page size, in any case.

Firebird provides two pre-defined subtypes for storing user data:. The alias for subtype zero is BINARY. This is the subtype to specify when the data are any form of binary file or stream: images, audio, word-processor files, PDFs and so on.

Subtype 1 has an alias, TEXT , which can be used in declarations and definitions. It is a specialized subtype used to store plain text data that is too large to fit into a string type. A CHARACTER SET may be specified, if the field is to store text with a different encoding to that specified for the database. From Firebird 2. It is also possible to add custom data subtypes, for which the range of enumeration from -1 to , is reserved. Custom subtypes enumerated with positive numbers are not allowed, as the Firebird engine uses the numbers from 2-upward for some internal subtypes in metadata.

The maximum size of a BLOB field is limited to 4GB, regardless of whether the server is bit or bit. The internal structures related to BLOB s maintain their own 4-byte counters. The following operators are supported completely:. Aggregation clauses work not on the contents of the field itself, but on the BLOB ID.

Aside from that, there are some quirks:. concatenates the same strings if they are adjacent to each other, but does not do it if they are remote from each other. By default, a regular record is created for each BLOB and it is stored on a data page that is allocated for it.

If the entire BLOB fits onto this page, it is called a level 0 BLOB. The number of this special record is stored in the table record and occupies 8 bytes.

If a BLOB does not fit onto one data page, its contents are put onto separate pages allocated exclusively to it blob pages , while the numbers of these pages are stored into the BLOB record. This is a level 1 BLOB. If the array of page numbers containing the BLOB data does not fit onto a data page, the array is put on separate blob pages, while the numbers of these pages are put into the BLOB record. This is a level 2 BLOB. FILTER , DECLARE FILTER. The support of arrays in the Firebird DBMS is a departure from the traditional relational model.

Supporting arrays in the DBMS could make it easier to solve some data-processing tasks involving large sets of similar data. Arrays in Firebird are stored in BLOB of a specialized type. Arrays can be one-dimensional and multidimensional and of any data type except BLOB and ARRAY.

This example will create a table with a field of the array type consisting of four integers. The subscripts of this array are from 1 to 4. To specify explicit upper and lower bounds of the subscript values, use the following syntax:.

A new dimension is added using a comma in the syntax. In this example we create a table with a two-dimensional array, with the lower bound of subscripts in both dimensions starting from zero:. The DBMS does not offer much in the way of language or tools for working with the contents of arrays. The database employee. fdb , found in the.. If the features described are enough for your tasks, you might consider using arrays in your projects. Currently, no improvements are planned to enhance support for arrays in Firebird.

It is not available as a data type for declaring table fields, PSQL variables or parameter descriptions. It was added to support the use of untyped parameters in expressions involving the IS NULL predicate. An evaluation problem occurs when optional filters are used to write queries of the following type:. This is a case where the developer writes an SQL query and considers :param1 as though it were a variable that he can refer to twice. The server cannot determine the type of the second parameter since it comes in association with IS NULL.

The following example demonstrates its use in practice. Each named parameter corresponds with two positional parameters in the query.

The application passes the parameterized query to the server in the usual positional? in our example. Firebird has no knowledge of their special relation with the first and third parameters: that responsibility lies entirely on the application side.

Once the values for size and colour have been set or left unset by the user and the query is about to be executed, each pair of XSQLVAR s must be filled as follows:. In other words: The value compare parameter is always set as usual. When composing an expression or specifying an operation, the aim should be to use compatible data types for the operands. When a need arises to use a mixture of data types, it should prompt you to look for a way to convert incompatible operands before subjecting them to the operation.

The ability to convert data may well be an issue if you are working with Dialect 1 data. When you cast to a domain, any constraints declared for it are taken into account, i.

If the value does not pass the check, the cast will fail. When operands are cast to the type of a column, the specified column may be from a table or a view. Only the type of the column itself is used. For character types, the cast includes the character set, but not the collation. The constraints and default values of the source column are not applied. Keep in mind that partial information loss is possible.

For instance, when you cast the TIMESTAMP data type to the DATE data type, the time-part is lost. To cast string data types to the DATE , TIME or TIMESTAMP data types, you need the string argument to be one of the predefined date and time literals see Table 9 or a representation of the date in one of the allowed date-time literal formats:.

It may contain 1 or 2 digits or You can also specify the three-letter shorthand name or the full name of a month in English.

A separator, any of permitted characters. Leading and trailing spaces are ignored. These shorthand expressions are evaluated directly during parsing, as though the statement were already prepared for execution. Thus, even if the query is run several times, the value of, for instance, timestamp 'now' remains the same no matter how much time passes.

If you need the time to be evaluated at each execution, use the full CAST syntax. An example of using such an expression in a trigger:. In Dialect 1, in many expressions, one type is implicitly cast to another without the need to use the CAST function.

For instance, the following statement in Dialect 1 is valid:. In Dialect 1, mixing integer data and numeric strings is usually possible because the parser will try to cast the string implicitly. For example,. In Dialect 3, an expression like this will raise an error, so you will need to write it as a CAST expression:.

When multiple data elements are being concatenated, all non-string data will undergo implicit conversion to string, if possible. Creating a domain does not truly create a new data type, of course. If several tables need columns defined with identical or nearly identical attributes, a domain makes sense.

Domain usage is not limited to column definitions for tables and views. Domains can be used to declare input and output parameters and variables in PSQL code. A domain definition contains required and optional attributes. The data type is a required attribute. Optional attributes include:. Explicit Data Type Conversion for the description of differences in the data conversion mechanism when domains are specified for the TYPE OF and TYPE OF COLUMN modifiers.

While defining a column using a domain, it is possible to override some of the attributes inherited from the domain. Table 3. To add new conditions to the check, you can use the corresponding CHECK clauses in the CREATE and ALTER statements at the table level. Often it is better to leave domain nullable in its definition and decide whether to make it NOT NULL when using the domain to define columns.

CREATE DOMAIN in the Data Definition Language DDL section. To change the attributes of a domain, use the DDL statement ALTER DOMAIN. With this statement you can:. If you change domains in haste, without carefully checking them, your code may stop working!

When you convert data types in a domain, you must not perform any conversions that may result in data loss. Also, for example, if you convert VARCHAR to INTEGER , check carefully that all data using this domain can be successfully converted.

ALTER DOMAIN in the Data Definition Language DDL section. The DDL statement DROP DOMAIN deletes a domain from the database, provided it is not in use by any other database objects.

DROP DOMAIN in the Data Definition Language DDL section. SQL expressions provide formal methods for evaluating, transforming and comparing values. SQL expressions may include table columns, variables, constants, literals, various statements and predicates and also other expressions.

The complete list of possible tokens in expressions follows. Identifier of a column from a specified table used in evaluations or as a search condition. A column of the array type cannot be an element in an expression except when used with the IS [NOT] NULL predicate. An expression may contain a reference to an array member i. The reserved words NOT , AND and OR , used to combine simple search conditions in order to create complex assertions. Predicates used to check the existence of values in a set.

The IN predicate can be used both with sets of comma-separated constants and with subqueries that return a single column. The EXISTS , SINGULAR , ALL , ANY and SOME predicates can be used only with subqueries. An expression, similar to a string literal enclosed in apostrophes, that can be interpreted as a date, time or timestamp value. Date literals can be predefined literals 'TODAY' , 'NOW' , etc. or strings of characters and numerals, such as ' Declared local variable, input or output parameter of a PSQL module stored procedure, trigger, unnamed PSQL block in DSQL.

A member of in an ordered group of one or more unnamed parameters passed to a stored procedure or prepared query. A SELECT statement enclosed in parentheses that returns a single scalar value or, when used in existential predicates, a set of values.

Operations inside the parentheses are performed before operations outside them. When nested parentheses are used, the most deeply nested expressions are evaluated first and then the evaluations move outward through the levels of nesting. Clause applied to CHAR and VARCHAR types to specify the character-set-specific collation sequence to use in string comparisons.

Expression for obtaining the next value of a specified generator sequence. A constant is a value that is supplied directly in an SQL statement, not derived from an expression, a parameter, a column reference nor a variable. It can be a string or a number. The maximum length of a string is 32, bytes; the maximum character count will be determined by the number of bytes used to encode each character.

Double quotes are NOT VALID for quoting strings. SQL reserves a different purpose for them. Care should be taken with the string length if the value is to be written to a VARCHAR column. The maximum length for a VARCHAR is 32, bytes. The character set of a string constant is assumed to be the same as the character set of its destined storage. Each pair of hex digits defines one byte in the string. Strings entered this way will have character set OCTETS by default, but the introducer syntax can be used to force a string to be interpreted as another character set.

The client interface determines how binary strings are displayed to the user. The isql utility, for example, uses upper case letters A-F, while FlameRobin uses lower case letters.

Other client programs may use other conventions, such as displaying spaces between the byte pairs: '4E 65 72 76 65 6E'. The hexadecimal notation allows any byte value including 00 to be inserted at any position in the string.

However, if you want to coerce it to anything other than OCTETS, it is your responsibility to supply the bytes in a sequence that is valid for the target character set. This is known as introducer syntax. Its purpose is to inform the engine about how to interpret and store the incoming string.

In SQL, for numbers in the standard decimal notation, the decimal point is always represented by period. Inclusion of commas, blanks, etc. will cause errors. Exponential notation is supported. For example, 0. Hexadecimal notation is supported by Firebird 2. Numbers with hex digits will be interpreted as type INTEGER ; numbers with hex digits as type BIGINT. Hex numbers in the range To coerce a number to BIGINT , prepend enough zeroes to bring the total number of hex digits to nine or above.

That changes the type but not the value. When written with eight hex digits, as in 0x9E44F9A8 , a value is interpreted as bit INTEGER. Since the leftmost bit sign bit is set, it maps to the negative range With one or more zeroes prepended, as in 0x09E44F9A8 , a value is interpreted as bit BIGINT in the range The sign bit is not set now, so they map to the positive range This is something to be aware of.

Hex numbers between FFFF FFFF FFFF FFFF are all negative BIGINT. A SMALLINT cannot be written in hex, strictly speaking, since even 0x1 is evaluated as INTEGER. However, if you write a positive integer within the bit range 0x decimal zero to 0x7FFF decimal it will be converted to SMALLINT transparently.

It is possible to write to a negative SMALLINT in hex, using a 4-byte hex number within the range 0xFFFF decimal to 0xFFFFFFFF decimal SQL operators comprise operators for comparing, calculating, evaluating and concatenating values.

SQL Operators are divided into four types. Each operator type has a precedence , a ranking that determines the order in which operators and the values obtained with their help are evaluated in an expression.

The higher the precedence of the operator type is, the earlier it will be evaluated. Each operator has its own precedence within its type, that determines the order in which they are evaluated in an expression. Operators with the same precedence are evaluated from left to right. To force a different evaluation order, operations can be grouped by means of parentheses. Arithmetic operations are performed after strings are concatenated, but before comparison and logical operations.

Comparison operations take place after string concatenation and arithmetic operations, but before logical operations. Character strings can be constants or values obtained from columns or other expressions. Combines two or more predicates, each of which must be true for the entire predicate to be true. Combines two or more predicates, of which at least one predicate must be true for the entire predicate to be true.

NEXT VALUE FOR returns the next value of a sequence. SEQUENCE is an SQL-compliant term for a generator in Firebird and its ancestor, InterBase. A step value of 0 returns the current sequence value.

A conditional expression is one that returns different values according to how a certain condition is met. It is composed by applying a conditional function construct, of which Firebird supports several. This section describes only one conditional expression construct: CASE. All other conditional expressions apply internal functions derived from CASE and are described in Conditional Functions.

The CASE construct returns a single value from a number of possible ones. Two syntactic variants are supported:. The simple CASE , comparable to a case construct in Pascal or a switch in C. When this variant is used, test-expr is compared expr 1, expr 2 etc. If no match is found, defaultresult from the optional ELSE clause is returned.

If there are no matches and no ELSE clause, NULL is returned. That is, if test-expr is NULL , it does not match any expr , not even an expression that resolves to NULL. The returned result does not have to be a literal value: it might be a field or variable name, compound expression or NULL literal. A short form of the simple CASE construct is the DECODE function. The first expression to return TRUE determines the result. If no expressions return TRUE , defaultresult from the optional ELSE clause is returned as the result.

If no expressions return TRUE and there is no ELSE clause, the result will be NULL. As with the simple CASE construct, the result need not be a literal value: it might be a field or variable name, a compound expression, or be NULL.

NULL is not a value in SQL, but a state indicating that the value of the element either is unknown or it does not exist. When you use NULL in logical Boolean expressions, the result will depend on the type of the operation and on other participating values. When you compare a value to NULL , the result will be unknown. NULL means NULL but, in Firebird, the logical result unknown is also represented by NULL. It has already been shown that NOT NULL results in NULL.

The interaction is a bit more complicated for the logical AND and logical OR operators:. Up to and including Firebird 2. However, there are logical expressions predicates that can return true, false or unknown. A subquery is a special form of expression that is actually a query embedded within another query.

Subqueries are written in the same way as regular SELECT queries, but they must be enclosed in parentheses. Subquery expressions can be used in the following ways:. To obtain values or conditions for search predicates the WHERE , HAVING clauses.

To produce a set that the enclosing query can select from, as though were a regular table or view. Subqueries like this appear in the FROM clause derived tables or in a Common Table Expression CTE. A subquery can be correlated. A query is correlated when the subquery and the main query are interdependent. To process each record in the subquery, it is necessary to fetch a record in the main query; i.

When subqueries are used to get the values of the output column in the SELECT list, a subquery must return a scalar result. Subqueries used in search predicates, other than existential and quantified predicates, must return a scalar result; that is, not more than one column from not more than one matching row or aggregation.

Although it is reporting a genuine error, the message can be slightly misleading. If P resolves as TRUE, it succeeds. If it resolves to FALSE or NULL UNKNOWN , it fails. A trap lies here, though: suppose the predicate, P , returns FALSE. In this case NOT P will return TRUE. On the other hand, if P returns NULL unknown , then NOT P returns NULL as well. In SQL, predicates can appear in CHECK constraints, WHERE and HAVING clauses, CASE expressions, the IIF function and in the ON condition of JOIN clauses.

An assertion is a statement about the data that, like a predicate, can resolve to TRUE, FALSE or NULL. Assertions consist of one or more predicates, possibly negated using NOT and connected by AND and OR operators. Parentheses may be used for grouping predicates and controlling evaluation order. A predicate may embed other predicates.

Evaluation sequence is in the outward direction, i. A comparison predicate consists of two expressions connected with a comparison operator. There are six traditional comparison operators:. For the complete list of comparison operators with their variant forms, see Comparison Operators.

If one of the sides left or right of a comparison predicate has NULL in it, the value of the predicate will be UNKNOWN. The following query will return no data, even if there are printers with no type specified for them, because a predicate that compares NULL with NULL returns NULL :.

On the other hand, ptrtype can be tested for NULL and return a result: it is just that it is not a comparison test:. When CHAR and VARCHAR fields are compared for equality, trailing spaces are ignored in all cases.

The BETWEEN predicate tests whether a value falls within a specified range of two values. NOT BETWEEN tests whether the value does not fall within that range.

The operands for BETWEEN predicate are two arguments of compatible data types. The search is inclusive the values represented by both arguments are included in the search. In other words, the BETWEEN predicate could be rewritten:. When BETWEEN is used in the search conditions of DML queries, the Firebird optimizer can use an index on the searched column, if it is available. The LIKE predicate compares the character-type expression with the pattern defined in the second expression.

Case- or accent-sensitivity for the comparison is determined by the collation that is in use. A collation can be specified for either operand, if required. If the tested value matches the pattern, taking into account wildcard symbols, the predicate is TRUE. If the search string contains either of the wildcard symbols, the ESCAPE clause can be used to specify an escape character.

Actually, the LIKE predicate does not use an index. So, if you need to search for the beginning of a string, it is recommended to use the STARTING WITH predicate instead of the LIKE predicate. Search for tables containing the underscore character in their names.

The STARTING WITH predicate searches for a string or a string-like type that starts with the characters in its value argument. The search is case-sensitive. When STARTING WITH is used in the search conditions of DML queries, the Firebird optimizer can use an index on the searched column, if it exists.

It can be used for an alphanumeric string-like search on numbers and dates. However, if an accent-sensitive collation is in use then the search will be accent-sensitive. Search for changes in salaries with the date containing number 84 in this case, it means changes that took place in :. SIMILAR TO matches a string against an SQL regular expression pattern. If any operand is NULL , the result is NULL.

Otherwise, the result is TRUE or FALSE. The following syntax defines the SQL regular expression format. It is a complete and correct top-down definition. Feel free to skip it and read the next section, Building Regular Expressions , which uses a bottom-up approach, aimed at the rest of us.

Within regular expressions, most characters represent themselves. The only exceptions are the special characters below:. A regular expression that contains no special or escape characters matches only strings that are identical to itself subject to the collation in use. A bunch of characters enclosed in brackets define a character class.

A character in the string matches a class in the pattern if the character is a member of the class:. Within a class definition, two characters connected by a hyphen define a range.

A range comprises the two endpoints and all the characters that lie between them in the active collation. Ranges can be placed anywhere in the class definition without special delimiters to keep them apart from the other elements. Latin letters a.. z and A.. With an accent-insensitive collation, this class also matches accented forms of these characters.

Uppercase Latin letters A.. Also matches lowercase with case-insensitive collation and accented forms with accent-insensitive collation. Lowercase Latin letters a.. Also matches uppercase with case-insensitive collation and accented forms with accent-insensitive collation. Matches horizontal tab ASCII 9 , linefeed ASCII 10 , vertical tab ASCII 11 , formfeed ASCII 12 , carriage return ASCII 13 and space ASCII Including a predefined class has the same effect as including all its members.

Predefined classes are only allowed within class definitions. If you need to match against a predefined class and nothing more, place an extra pair of brackets around it. If a class definition starts with a caret, everything that follows is excluded from the class. All other characters match:.

If the caret is not placed at the start of the sequence, the class contains everything before the caret, except for the elements that also occur after the caret:. If the braces contain two numbers separated by a comma, the second number not smaller than the first, then the item must be repeated at least the first number and at most the second number of times in order to match:.

A match is made when the argument string matches at least one of the terms:. A subexpression is a regular expression in its own right. It can contain all the elements allowed in a regular expression, and can also have quantifiers added to it. In order to match against a character that is special in regular expressions, that character has to be escaped. There is no default escape character; rather, the user specifies one when needed:.

Two operands are considered DISTINCT if they have a different value or if one of them is NULL and the other non-null. They are NOT DISTINCT if they have the same value or if both of them are NULL. Since NULL is not a value, these operators are not comparison operators. The IS [NOT] NULL predicate tests the assertion that the expression on the left side has a value IS NOT NULL or has no value IS NULL. In Firebird 3. This group of predicates includes those that use subqueries to submit values for all kinds of assertions in search conditions.

Existential predicates are so called because they use various methods to test for the existence or non-existence of some assertion, returning TRUE if the existence or non-existence is confirmed or FALSE otherwise.

The EXISTS predicate uses a subquery expression as its argument. It returns TRUE if the subquery result would contain at least one row; otherwise it returns FALSE. NOT EXISTS returns FALSE if the subquery result would contain at least one row; it returns TRUE otherwise.

The IN predicate tests whether the value of the expression on the left side is present in the set of values specified on the right side. The set of values cannot have more than items. The IN predicate can be replaced with the following equivalent forms:. When the IN predicate is used in the search conditions of DML queries, the Firebird optimizer can use an index on the searched column, if a suitable one exists.

Queries specified using the IN predicate with a subquery can be replaced with a similar query using the EXISTS predicate. For instance, the following query:. However, a query using NOT IN with a subquery does not always give the same result as its NOT EXISTS counterpart.

The reason is that EXISTS always returns TRUE or FALSE, whereas IN returns NULL in one of these two cases:. when the test value has no match in the IN list and at least one list element is NULL. It is in only these two cases that IN will return NULL while the corresponding EXISTS predicate will return FALSE 'no matching row found'.

But, for the same data, NOT IN will return NULL , while NOT EXISTS will return TRUE , leading to opposite results. Now, assume that the NY celebrities list is not empty and contains at least one NULL birthday. Then for every citizen who does not share his birthday with a NY celebrity, NOT IN will return NULL , because that is what IN does. The search condition is thereby not satisfied and the citizen will be left out of the SELECT result, which is wrong.

non-matches will have a NOT EXISTS result of TRUE and their records will be in the result set. If there is any chance of NULL s being encountered when searching for a non-match, you will want to use NOT EXISTS. The SINGULAR predicate takes a subquery as its argument and evaluates it as TRUE if the subquery returns exactly one result row; otherwise the predicate is evaluated as FALSE. The subquery may list several output columns since the rows are not returned anyway.

They are only tested for singular existence. The SINGULAR predicate can return only two values: TRUE or FALSE. A quantifier is a logical operator that sets the number of objects for which this assertion is true. It is not a numeric quantity, but a logical one that connects the assertion with the full set of possible objects.

Such predicates are based on logical universal and existential quantifiers that are recognised in formal logic. In subquery expressions, quantified predicates make it possible to compare separate values with the results of subqueries; they have the following common form:. When the ALL quantifier is used, the predicate is TRUE if every value returned by the subquery satisfies the condition in the predicate of the main query. If the subquery returns an empty set, the predicate is TRUE for every left-side value, regardless of the operator.

This may appear to be contradictory, because every left-side value will thus be considered both smaller and greater than, both equal to and unequal to, every element of the right-side stream.

Nevertheless, it aligns perfectly with formal logic: if the set is empty, the predicate is true 0 times, i. The quantifiers ANY and SOME are identical in their behaviour. Apparently, both are present in the SQL standard so that they could be used interchangeably in order to improve the readability of operators.

When the ANY or the SOME quantifier is used, the predicate is TRUE if any of the values returned by the subquery satisfies the condition in the predicate of the main query.

If the subquery would return no rows at all, the predicate is automatically considered as FALSE. DDL statements are used to create, modify and delete database objects that have been created by users. When a DDL statement is committed, the metadata for the object are created, changed or deleted. This section describes how to create a database, connect to an existing database, alter the file structure of a database and how to delete one. Optionally includes a port number or service name.

Full path and file name including its extension. The file name must be specified according to the rules of the platform file system being used. Database alias previously created in the aliases. conf file. User name of the owner of the new database.

It may consist of up to 31 characters. Password of the user name as the database owner. The maximum length is 31 characters; however only the first 8 characters are considered. Page size for the database, in bytes.

Possible values are the default , and Specifies the character set of the connection available to a client connecting after the database is successfully created. Single quotes are required. The CREATE DATABASE statement creates a new database. You can use CREATE DATABASE or CREATE SCHEMA. They are synonymous. A database may consist of one or several files.

The first main file is called the primary file , subsequent files are called secondary file[s]. Nowadays, multi-file databases are considered an anachronism. It made sense to use multi-file databases on old file systems where the size of any file is limited. For instance, you could not create a file larger than 4 GB on FAT The primary file specification is the name of the database file and its extension with the full path to it according to the rules of the OS platform file system being used.

The database file must not exist at the moment when the database is being created. If it does exist, you will get an error message and the database will not be created. If the full path to the database is not specified, the database will be created in one of the system directories. The particular directory depends on the operating system. For this reason, unless you have a strong reason to prefer that situation, always specify the absolute path, when creating either the database or an alias for it.

You can use aliases instead of the full path to the primary database file. If you create a database on a remote server, you should specify the remote server specification. The remote server specification depends on the protocol being used. If you use the Named Pipes protocol to create a database on a Windows server, the primary file specification should look like this:.

Clauses for specifying the user name and the password, respectively, of an existing user in the security database security2. The user specified in the process of creating the database will be its owner. This will be important when considering database and object privileges.

Clause for specifying the database page size. This size will be set for the primary file and all secondary files of the database. If you specify the database page size less than 4,, it will be changed automatically to the default page size, 4, Other values not equal to either 4,, 8, or 16, will be changed to the closest smaller supported value.

If the database page size is not specified, it is set to the default value of 4, Clause specifying the maximum size of the primary or secondary database file, in pages. When a database is created, its primary and secondary files will occupy the minimum number of pages necessary to store the system data, regardless of the value specified in the LENGTH clause.

The LENGTH value does not affect the size of the only or last, in a multi-file database file. The file will keep increasing its size automatically when necessary. Clause specifying the character set of the connection available after the database is successfully created. The character set NONE is used by default. Notice that the character set should be enclosed in a pair of apostrophes single quotes.

Clause specifying the default character set for creating data structures of string data types. Character sets are applied to CHAR , VARCHAR and BLOB TEXT data types. It is also possible to specify the default COLLATION for the default character set, making that collation sequence the default for the default character set. The default will be used for the entire database except where an alternative character set, with or without a specified collation, is used explicitly for a field, domain, variable, cast expression, etc.

Clause that specifies the database page number at which the next secondary database file should start. When the previous file is completely filled with data according to the specified page number, the system will start adding new data to the next database file. For the detailed description of this clause, see ALTER DATABASE. Databases are created in Dialect 3 by default. For the database to be created in SQL dialect 1, you will need to execute the statement SET SQL DIALECT 1 from script or the client application, e.

in isql , before the CREATE DATABASE statement. Creating a database in Windows, located on disk D with a page size of 8, The owner of the database will be the user wizard. The database will be in Dialect 1 and it will use WIN as its default character set. Creating a database in the Linux operating system with a page size of 4, The database will be in Dialect 3 and will use UTF8 as its default character set.

Creating a database in Dialect 3 with UTF8 as its default character set. The primary file will contain up to 10, pages with a page size of 8, As soon as the primary file has reached the maximum number of pages, Firebird will start allocating pages to the secondary file test.

If that file is filled up to its maximum as well, test. fdb3 becomes the recipient of all new page allocations. As the last file, it has no page limit imposed on it by Firebird. Let source text be the result of decoding bodyBytes to Unicode, using character encoding as the fallback encoding.

The decode algorithm overrides character encoding if the file contains a BOM. Let muted errors be true if response was CORS-cross-origin , and false otherwise. Let script be the result of creating a classic script given source text , settings object , response 's URL , options , and muted errors.

Run onComplete given script. To fetch a classic worker script given a url , a fetch client settings object , a destination , a script settings object , an onComplete algorithm, and an optional perform the fetch hook performFetch , run these steps. Let request be a new request whose URL is url , client is fetch client settings object , destination is destination , initiator type is " other ", mode is " same-origin ", credentials mode is " same-origin ", parser metadata is " not parser-inserted ", and whose use-URL-credentials flag is set.

If performFetch was given, run performFetch with request , true, and with processResponseConsumeBody as defined below. Otherwise, fetch request with processResponseConsumeBody set to processResponseConsumeBody as defined below. In both cases, let processResponseConsumeBody given response response and null, failure, or a byte sequence bodyBytes be the following algorithm:.

response 's URL 's scheme is an HTTP S scheme ; and the result of extracting a MIME type from response 's header list is not a JavaScript MIME type ,. Other fetch schemes are exempted from MIME type checking for historical web-compatibility reasons. We might be able to tighten this in the future; see issue Let source text be the result of UTF-8 decoding bodyBytes. Let script be the result of creating a classic script using source text , script settings object , response 's URL , and the default classic script fetch options.

To fetch a classic worker-imported script given a url , a settings object , and an optional perform the fetch hook performFetch , run these steps. The algorithm will synchronously complete with a classic script on success, or throw an exception on failure. Let response be null. Let bodyBytes be null. Let request be a new request whose URL is url , client is settings object , destination is " script ", initiator type is " other ", parser metadata is " not parser-inserted ", and whose use-URL-credentials flag is set.

If performFetch was given, run performFetch with request , isTopLevel , and with processResponseConsumeBody as defined below. In both cases, let processResponseConsumeBody given response res and null, failure, or a byte sequence bb be the following algorithm:. Set bodyBytes to bb. Set response to res. Pause until response is not null. Unlike other algorithms in this section, the fetching process is synchronous here.

If any of the following conditions are met:. bodyBytes is null or failure; response 's status is not an ok status ; or the result of extracting a MIME type from response 's header list is not a JavaScript MIME type ,.

then throw a " NetworkError " DOMException. Let script be the result of creating a classic script given source text , settings object , response 's URL , the default classic script fetch options , and muted errors. Return script. To fetch an external module script graph given a url , a settings object , some options , and an onComplete algorithm, run these steps.

onComplete must be an algorithm accepting null on failure or a module script on success. Disallow further import maps given settings object.

Fetch a single module script given url , settings object , " script ", options , settings object , " client ", true, and with the following steps given result :.

If result is null, run onComplete given null, and abort these steps. Let visited set be « url , " javascript " ».

Fetch the descendants of and link result given settings object , " script ", visited set , and onComplete. To fetch an import module script graph given a moduleRequest , a script , a settings object , some options , and an onComplete algorithm, run these steps. Let url be the result of resolving a module specifier given script and moduleRequest.

If the previous step threw an exception, then run onComplete given null, and return. Assert : moduleRequest. Let moduleType be the result of running the module type from module request steps given moduleRequest.

If the result of running the module type allowed steps given moduleType and settings object is false, then run onComplete given null, and return. Fetch a single module script given url , settings object , " script ", options , settings object , " client ", moduleRequest , true, and with the following steps given result :.

If result is null, run onComplete with null, and abort these steps. Let visited set be « url , moduleType ». Fetch the descendants of and link result given settings object , destination , visited set , and onComplete. To fetch a modulepreload module script graph given a url , a destination , a settings object , some options , and an onComplete algorithm, run these steps. Fetch a single module script given url , settings object , destination , options , settings object , " client ", true, and with the following steps given result :.

Run onComplete given result. If result is not null, optionally perform the following steps:. Fetch the descendants of and link result given settings object , destination , visited set , and with an empty algorithm. Generally, performing these steps will be beneficial for performance, as it allows pre-loading the modules that will invariably be requested later, via algorithms such as fetch an external module script graph that fetch the entire graph.

However, user agents might wish to skip them in bandwidth-constrained situations, or situations where the relevant fetches are already in flight.

To fetch an inline module script graph given a source text , base URL , settings object , options , and an onComplete algorithm, run these steps. Let script be the result of creating a JavaScript module script using source text , settings object , base URL , and options. If script is null, run onComplete given null, and return. Let visited set be an empty set. Fetch the descendants of and link script , given settings object , the destination " script ", visited set , and onComplete.

Let requestURL be request 's URL. If moduleResponsesMap [ requestURL ] is " fetching ", wait in parallel until that entry's value changes, then queue a task on the networking task source to proceed with running the following steps. If moduleResponsesMap [ requestURL ] exists , then:. Let cached be moduleResponsesMap [ requestURL ]. Run processCustomFetchResponse with cached [0] and cached [1].

Set moduleResponsesMap [ requestURL ] to " fetching ". Fetch request , with processResponseConsumeBody set to the following steps given response response and null, failure, or a byte sequence bodyBytes :. Set moduleResponsesMap [ requestURL ] to response , bodyBytes.

Run processCustomFetchResponse with response and bodyBytes. The following algorithms are meant for internal use by this specification only as part of fetching an external module script graph or other similar concepts above, and should not be used directly by other specifications. This diagram illustrates how these algorithms relate to the ones above, as well as to each other:. Let options be a script fetch options whose cryptographic nonce is the empty string, integrity metadata is the empty string, parser metadata is " not-parser-inserted ", credentials mode is credentials mode , and referrer policy is the empty string.

Fetch a single module script given url , fetch client settings object , destination , options , module map settings object , " client ", true, and onSingleFetchComplete as defined below. If performFetch was given, pass it along as well. onSingleFetchComplete given result is the following algorithm:. Fetch the descendants of and link result given fetch client settings object , destination , visited set , and onComplete. To fetch the descendants of and link a module script module script , given a fetch client settings object , a destination , a visited set , an onComplete algorithm, and an optional perform the fetch hook performFetch , run these steps.

Fetch the descendants of module script , given fetch client settings object , destination , visited set , and onFetchDescendantsComplete as defined below. If result is null, then run onComplete given result , and abort these steps. In this case, there was an error fetching one or more of the descendants. We will not attempt to link. Let parse error be the result of finding the first parse error given result. If parse error is null, then:.

Let record be result 's record. Perform record. This step will recursively call Link on all of the module's unlinked dependencies. If this throws an exception, set result 's error to rethrow to that exception. Otherwise, set result 's error to rethrow to parse error. To fetch the descendants of a module script module script , given a fetch client settings object , a destination , a visited set , an onComplete algorithm, and an optional perform the fetch hook performFetch , run these steps.

If module script 's record is null, run onComplete with module script and return. Let record be module script 's record. If record is not a Cyclic Module Record , or if record.

Let moduleRequests be a new empty list. For each ModuleRequest Record requested of record. Let url be the result of resolving a module specifier given module script and requested. Assert : the previous step never throws an exception, because resolving a module specifier must have been previously successful with these same two arguments.

Let moduleType be the result of running the module type from module request steps given requested. If visited set does not contain url , moduleType , then:. Append requested to moduleRequests. Append url , moduleType to visited set. Let options be the descendant script fetch options for module script 's fetch options.

Assert : options is not null, as module script is a JavaScript module script. Let pendingCount be the length of moduleRequests. If pendingCount is zero, run onComplete with module script. Let failed be false. For each moduleRequest in moduleRequests , perform the internal module script graph fetching procedure given moduleRequest , fetch client settings object , destination , options , module script , visited set , and onInternalFetchingComplete as defined below.

If failed is true, then abort these steps. If result is null, then set failed to true, run onComplete with null, and abort these steps. Assert : pendingCount is greater than zero. Decrement pendingCount by one. The fetches performed by the internal module script graph fetching procedure are performed in parallel to each other.

To perform the internal module script graph fetching procedure given a moduleRequest , a fetch client settings object , a destination , some options , a referringScript , a visited set , an onComplete algorithm, and an optional perform the fetch hook performFetch , run these steps. Let url be the result of resolving a module specifier given referringScript and moduleRequest. Assert : visited set contains url , moduleType. Fetch a single module script given url , fetch client settings object , destination , options , referringScript 's settings object , referringScript 's base URL , moduleRequest , false, and onSingleFetchComplete as defined below.

Fetch the descendants of result given fetch client settings object , destination , visited set , and with onComplete. To fetch a single module script , given a url , a fetch client settings object , a destination , some options , a module map settings object , a referrer , an optional moduleRequest , a boolean isTopLevel , an onComplete algorithm, and an optional perform the fetch hook performFetch , run these steps.

Let moduleType be " javascript ". If moduleRequest was given, then set moduleType to the result of running the module type from module request steps given moduleRequest. Assert : the result of running the module type allowed steps given moduleType and module map settings object is true. Otherwise we would not have reached this point because a failure would have been raised when inspecting moduleRequest.

Let moduleMap be module map settings object 's module map. If moduleMap [ url , moduleType ] is " fetching ", wait in parallel until that entry's value changes, then queue a task on the networking task source to proceed with running the following steps. If moduleMap [ url , moduleType ] exists , run onComplete given moduleMap [ url , moduleType ], and return.

Set moduleMap [ url , moduleType ] to " fetching ". Let request be a new request whose URL is url , destination is destination , mode is " cors ", referrer is referrer , and client is fetch client settings object. If destination is " worker ", " sharedworker ", or " serviceworker ", and the top-level module fetch flag is set, then set request 's mode to " same-origin ".

Set up the module script request given request and options. response is always CORS-same-origin. bodyBytes is null or failure; or response 's status is not an ok status , then set moduleMap [ url , moduleType ] to null, run onComplete given null, and abort these steps. Let MIME type be the result of extracting a MIME type from response 's header list. Let module script be null. If MIME type is a JavaScript MIME type and moduleType is " javascript ", then set module script to the result of creating a JavaScript module script given source text , module map settings object , response 's URL , and options.

If MIME type essence is a JSON MIME type and moduleType is " json ", then set module script to the result of creating a JSON module script given source text and module map settings object. Set moduleMap [ url , moduleType ] to module script , and run onComplete given module script.

It is intentional that the module map is keyed by the request URL , whereas the base URL for the module script is set to the response URL. The former is used to deduplicate fetches, while the latter is used for URL resolution. To find the first parse error given a root moduleScript and an optional discoveredSet :. Let moduleMap be moduleScript 's settings object 's module map.

If discoveredSet was not given, let it be an empty set. Append moduleScript to discoveredSet. If moduleScript 's record is null, then return moduleScript 's parse error. If moduleScript 's record is not a Cyclic Module Record , then return null. Let moduleRequests be the value of moduleScript 's record 's [[RequestedModules]] internal slot.

For each moduleRequest of moduleRequests :. Let childURL be the result of resolving a module specifier given moduleScript and moduleRequest. This will never throw an exception, as otherwise moduleScript would have been marked as itself having a parse error. Let childModule be moduleMap [ childURL , moduleType ].

Assert : childModule is a module script i. If discoveredSet already contains childModule , continue. Let childParseError be the result of finding the first parse error given childModule and discoveredSet.

If childParseError is not null, return childParseError. Return null. If mutedErrors is true, then set baseURL to about:blank. When mutedErrors is true, baseURL is the script's CORS-cross-origin response 's url , which shouldn't be exposed to JavaScript.

Therefore, baseURL is sanitized here. If scripting is disabled for settings , then set source to the empty string. Let script be a new classic script that this algorithm will subsequently initialize. Set script 's settings object to settings. Set script 's base URL to baseURL. Set script 's fetch options to options. Set script 's muted errors to mutedErrors. Set script 's parse error and error to rethrow to null.

Let result be ParseScript source , settings 's realm , script. Passing script as the last parameter here ensures result. If result is a list of errors, then: Set script 's parse error and its error to rethrow to result [0]. Set script 's record to result. To create a JavaScript module script , given a string source , an environment settings object settings , a URL baseURL , and some script fetch options options :.

Let script be a new module script that this algorithm will subsequently initialize. Let result be ParseModule source , settings 's realm , script. If result is a list of errors, then:. Set script 's parse error to result [0]. Assert : requested. For each ModuleRequest record requested of result. Let url be the result of resolving a module specifier given script and requested. If the previous step threw an exception, then:. Set script 's parse error to that exception.

If the result of running the module type allowed steps given moduleType and settings is false, then:. Let error be a new TypeError exception. Set script 's parse error to error. This step is essentially validating all of the requested module specifiers and type assertions. We treat a module with unresolvable module specifiers or unsupported type assertions the same as one that cannot be parsed; in both cases, a syntactic issue makes it impossible to ever contemplate linking the module later.

To create a CSS module script , given a string source and an environment settings object settings :. Set script 's base URL and fetch options to null. Let sheet be the result of running the steps to create a constructed CSSStyleSheet with an empty dictionary as the argument. Run the steps to synchronously replace the rules of a CSSStyleSheet on sheet given source. If this throws an exception, set script 's parse error to that exception, and return script. The steps to synchronously replace the rules of a CSSStyleSheet will throw if source contains any import rules.

This is by-design for now because there is not yet an agreement on how to handle these for CSS module scripts; therefore they are blocked altogether until a consensus is reached. Set script 's record to the result of CreateDefaultExportSyntheticModule sheet.

To create a JSON module script , given a string source and an environment settings object settings :. Let result be ParseJSONModule source. The module type from module request steps, given a ModuleRequest Record moduleRequest , are as follows:. If moduleRequest. If entry. This specification uses the " javascript " module type internally for JavaScript module scripts , so this step is needed to prevent modules from being imported using a " javascript " type assertion a null moduleType will cause the module type allowed check to fail.

Otherwise, set moduleType to entry. Return moduleType. The module type allowed steps, given a string moduleType and an environment settings object settings , are as follows:. If moduleType is not " javascript ", " css ", or " json ", then return false. If moduleType is " css " and the CSSStyleSheet interface is not exposed in settings 's realm , then return false. Return true. Let settings be the settings object of script.

Check if we can run script with settings. If this returns "do not run" then return NormalCompletion empty. Prepare to run script given settings. Let evaluationStatus be null. If script 's error to rethrow is not null, then set evaluationStatus to Completion { [[Type]]: throw, [[Value]]: script 's error to rethrow , [[Target]]: empty }.

Otherwise, set evaluationStatus to ScriptEvaluation script 's record. If ScriptEvaluation does not complete because the user agent has aborted the running script , leave evaluationStatus as null. If evaluationStatus is an abrupt completion , then:. If rethrow errors is true and script 's muted errors is false, then:. Clean up after running script with settings.

Rethrow evaluationStatus. If rethrow errors is true and script 's muted errors is true, then:. Throw a " NetworkError " DOMException.

Otherwise, rethrow errors is false. Perform the following steps:. Report the exception given by evaluationStatus. Return evaluationStatus. If evaluationStatus is a normal completion, then return evaluationStatus.

If we've reached this point, evaluationStatus was left as null because the script was aborted prematurely during evaluation. Return Completion { [[Type]]: throw, [[Value]]: a new " QuotaExceededError " DOMException , [[Target]]: empty }. To run a module script given a module script script and an optional boolean preventErrorReporting default false :. If this returns "do not run", then return a promise resolved with with undefined. Let evaluationPromise be null.

If script 's error to rethrow is not null, then set evaluationPromise to a promise rejected with script 's error to rethrow. Let record be script 's record. Set evaluationPromise to record. If Evaluate fails to complete as a result of the user agent aborting the running script , then set evaluationPromise to a promise rejected with a new " QuotaExceededError " DOMException.

If preventErrorReporting is false, then upon rejection of evaluationPromise with reason , report the exception given by reason for script. Return evaluationPromise. The steps to check if we can run script with an environment settings object settings are as follows. They return either "run" or "do not run".

If the global object specified by settings is a Window object whose Document object is not fully active , then return "do not run". If scripting is disabled for settings , then return "do not run". Return "run". The steps to prepare to run script with an environment settings object settings are as follows:. Push settings 's realm execution context onto the JavaScript execution context stack ; it is now the running JavaScript execution context.

Add settings to the currently running task 's script evaluation environment settings object set. The steps to clean up after running script with an environment settings object settings are as follows:. Assert : settings 's realm execution context is the running JavaScript execution context. Remove settings 's realm execution context from the JavaScript execution context stack. If the JavaScript execution context stack is now empty, perform a microtask checkpoint.

If this runs scripts, these algorithms will be invoked reentrantly. These algorithms are not invoked by one script directly calling another, but they can be invoked reentrantly in an indirect manner, e. if a script dispatches an event which has event listeners registered. The running script is the script in the [[HostDefined]] field in the ScriptOrModule component of the running JavaScript execution context.

Although the JavaScript specification does not account for this possibility, it's sometimes necessary to abort a running script. This causes any ScriptEvaluation or Source Text Module Record Evaluate invocations to cease immediately, emptying the JavaScript execution context stack without triggering any of the normal mechanisms like finally blocks.

User agents may impose resource limitations on scripts, for example CPU quotas, memory limits, total execution time limits, or bandwidth limitations.

When a script exceeds a limit, the user agent may either throw a " QuotaExceededError " DOMException , abort the script without an exception, prompt the user, or throttle script execution. For example, the following script never terminates.

A user agent could, after waiting for a few seconds, prompt the user to either terminate the script or let it continue. User agents are encouraged to allow users to disable scripting whenever the user is prompted either by a script e.

using the window. alert API or because of a script's actions e. because it has exceeded a time limit. If scripting is disabled while a script is executing, the script should be terminated immediately.

User agents may allow users to specifically disable scripts just for the purposes of closing a browsing context. For example, the prompt mentioned in the example above could also offer the user with a mechanism to just close the page entirely, without running any unload event handlers. reportError Support in all current engines.

Internet Explorer No Firefox Android? Safari iOS? Chrome Android? WebView Android? Samsung Internet? Opera Android? reportError e Dispatches an error event at the global object for the given value e , in the same fashion as an unhandled exception.

When the user agent is required to report an error for a particular script script with a particular position line : col , using a particular target target , it must run these steps, after which the error is either handled or not handled :. If target is in error reporting mode , then return; the error is not handled. Let target be in error reporting mode. Let message be an implementation-defined string describing the error in a helpful manner. Let errorValue be the value that represents the error: in the case of an uncaught exception, that would be the value that was thrown; in the case of a JavaScript error that would be an Error object.

If there is no corresponding value, then the null value must be used instead. Let urlString be the result of applying the URL serializer to the URL record that corresponds to the resource from which script was obtained. The resource containing the script will typically be the file from which the Document was parsed, e.

for inline script elements or event handler content attributes ; or the JavaScript file that the script was in, for external scripts. Even for dynamically-generated scripts, user agents are strongly encouraged to attempt to keep track of the original source of a script. For example, if an external script uses the document. write API to insert an inline script element during parsing, the URL of the resource containing the script would ideally be reported as being the external script, and the line number might ideally be reported as the line with the document.

write call or where the string passed to that call was first constructed. Naturally, implementing this can be somewhat non-trivial. User agents are similarly encouraged to keep careful track of the original line numbers, even in the face of document.

write calls mutating the document as it is parsed, or event handler content attributes spanning multiple lines. If script is a classic script and script 's muted errors is true, then set message to " Script error. Let notHandled be true. If target implements EventTarget , then set notHandled to the result of firing an event named error at target , using ErrorEvent , with the cancelable attribute initialized to true, the message attribute initialized to message , the filename attribute initialized to urlString , the lineno attribute initialized to line , the colno attribute initialized to col , and the error attribute initialized to errorValue.

Let target no longer be in error reporting mode. If notHandled is false, then the error is handled. Otherwise, the error is not handled. Returning true in an event handler cancels the event per the event handler processing algorithm. When the user agent is to report an exception E , the user agent must report the error for the relevant script , with the problematic position line number and column number in the resource containing the script, using the global object specified by the script's settings object as the target.

If the error is still not handled after this, then the error may be reported to a developer console. The existence of both report an error and report an exception is confusing, and both algorithms have known problems.

You can track future cleanup in this area in issue The reportError e method steps are to report the exception e. ErrorEvent Support in all current engines. The message attribute must return the value it was initialized to. It represents the error message.

The filename attribute must return the value it was initialized to. It represents the URL of the script in which the error originally occurred.

The lineno attribute must return the value it was initialized to. It represents the line number where the error occurred in the script. The colno attribute must return the value it was initialized to.

It represents the column number where the error occurred in the script. The error attribute must return the value it was initialized to. It must initially be initialized to undefined. Where appropriate, it is set to the object representing the error e. Safari iOS In addition to synchronous runtime script errors , scripts may experience asynchronous promise rejections, tracked via the unhandledrejection and rejectionhandled events.

Tracking these rejections is done via the HostPromiseRejectionTracker abstract operation, but reporting them is defined here. To notify about rejected promises on a given environment settings object settings object :. Let list be a copy of settings object 's about-to-be-notified rejected promises list. If list is empty, return. Clear settings object 's about-to-be-notified rejected promises list. Let global be settings object 's global object. Queue a global task on the DOM manipulation task source given global to run the following substep:.

If p 's [[PromiseIsHandled]] internal slot is true, continue to the next iteration of the loop. Let notHandled be the result of firing an event named unhandledrejection at global , using PromiseRejectionEvent , with the cancelable attribute initialized to true, the promise attribute initialized to p , and the reason attribute initialized to the value of p 's [[PromiseResult]] internal slot.

If notHandled is false, then the promise rejection is handled. Otherwise, the promise rejection is not handled. If p 's [[PromiseIsHandled]] internal slot is false, add p to settings object 's outstanding rejected promises weak set.

This algorithm results in promise rejections being marked as handled or not handled. These concepts parallel handled and not handled script errors.

If a rejection is still not handled after this, then the rejection may be reported to a developer console. PromiseRejectionEvent Support in all current engines. The PromiseRejectionEvent interface is defined as follows:. The promise attribute must return the value it was initialized to. It represents the promise which this notification is about.

The reason attribute must return the value it was initialized to. It represents the rejection reason for the promise.

An import map parse result is a struct that is similar to a script , and also can be stored in a script element's result , but is not counted as a script for other purposes.

It has the following items :. To create an import map parse result given a string input and a URL baseURL :. Let result be an import map parse result whose import map is null and whose error to rethrow is null. Parse an import map string given input and baseURL , catching any exceptions.

If this threw an exception, then set result 's error to rethrow to that exception. Otherwise, set result 's import map to the return value. Return result. To register an import map given a Window global and an import map parse result result :. If result 's error to rethrow is not null, then report the exception given by result 's error to rethrow and return.

Assert : global 's import map is an empty import map. Set global 's import map to result 's import map. When no import maps are involved, it is relatively straightforward, and reduces to resolving a URL-like module specifier. When there is a non-empty import map present, the behavior is more complex.

It checks candidate entries from all applicable module specifier maps , from most-specific to least-specific scopes falling back to the top-level unscoped imports , and from most-specific to least-specific prefixes. For each candidate, the resolve an imports match algorithm will give on the following results:. Successful resolution of the specifier to a URL. Then the resolve a module specifier algorithm will return that URL.

Throwing an exception. Then the resolve a module specifier algorithm will rethrow that exception, without any further fallbacks.

Failing to resolve, without an error. In this case the outer resolve a module specifier algorithm will move on to the next candidate. In the end, if no successful resolution is found via any of the candidate module specifier maps , resolve a module specifier will throw an exception. Thus the result is always either a URL or a thrown exception.

To resolve a module specifier given a script -or-null referringScript and a string specifier :. Let settingsObject and baseURL be null. If referringScript is not null, then:. Set settingsObject to referringScript 's settings object. Set baseURL to referringScript 's base URL. Assert : there is a current settings object. Set settingsObject to the current settings object.

Set baseURL to settingsObject 's API base URL. Let importMap be an empty import map. If settingsObject 's global object implements Window , then set importMap to settingsObject 's global object 's import map. Let baseURLString be baseURL , serialized. Let asURL be the result of resolving a URL-like module specifier given specifier and baseURL. Let normalizedSpecifier be the serialization of asURL , if asURL is non-null; otherwise, specifier.

Let scopeImportsMatch be the result of resolving an imports match given normalizedSpecifier , asURL , and scopeImports. If scopeImportsMatch is not null, then return scopeImportsMatch. Let topLevelImportsMatch be the result of resolving an imports match given normalizedSpecifier , asURL , and importMap 's imports. If topLevelImportsMatch is not null, then return topLevelImportsMatch. At this point, specifier wasn't remapped to anything by importMap , but it might have been able to be turned into a URL.

Throw a TypeError indicating that specifier was a bare specifier, but was not remapped to anything by importMap. To resolve an imports match , given a string normalizedSpecifier , a URL -or-null asURL , and a module specifier map specifierMap :.

If resolutionResult is null, then throw a TypeError indicating that resolution of specifierKey was blocked by a null entry. This will terminate the entire resolve a module specifier algorithm, without any further fallbacks.

Assert : resolutionResult is a URL. Return resolutionResult. If all of the following are true:. If resolutionResult is null, then throw a TypeError indicating that the resolution of specifierKey was blocked by a null entry. Let afterPrefix be the portion of normalizedSpecifier after the initial specifierKey prefix. Let url be the result of URL parsing afterPrefix with resolutionResult. If url is failure, then throw a TypeError indicating that resolution of normalizedSpecifier was blocked since the afterPrefix portion could not be URL-parsed relative to the resolutionResult mapped to by the specifierKey prefix.

Assert : url is a URL. If the serialization of resolutionResult is not a code unit prefix of the serialization of url , then throw a TypeError indicating that the resolution of normalizedSpecifier was blocked due to it backtracking above its prefix specifierKey. The resolve a module specifier algorithm will fall back to a less-specific scope, or to " imports ", if possible.

To resolve a URL-like module specifier , given a string specifier and a URL baseURL :. Let url be the result of URL parsing specifier with baseURL. If url is failure, then return null. One way this could happen is if specifier is ".. Return url.

Thus, url might end up with a different host than baseURL. Let url be the result of URL parsing specifier with no base URL. An import map allows control over module specifier resolution. Import maps are delivered via inline script elements with their type attribute set to " importmap ", and with their child text content containing a JSON representation of the import map.

Only one import map is processed per Document. After the first import map is seen, others will be ignored, with their corresponding script elements generating error events. Similarly, once any modules have been imported, e. These restrictions, as well as the lack of support for external import maps, are in place to keep the initial version of the feature simple.

They might be lifted over time as implementer bandwidth allows. js URL. An import map can remap a class of module specifiers into a class of URLs by using trailing slashes, like so:.

Such trailing-slash mappings are often combined with bare-specifier mappings, e. js " are available. Bare specifiers are not the only type of module specifiers which import maps can remap. They cannot be specified as relative URLs without those starting sigils, as those help distinguish from bare module specifiers. Also note how the trailing slash mapping works in this context as well.

Such remappings operate on the post-canonicalization URL, and do not require a match between the literal strings supplied in the import map key and the imported module specifier. mjs" be remapped, but so would import ". mjs" and import ".

All previous examples have globally remapped module specifiers, by using the top-level " imports " key in the import map. The top-level " scopes " key can be used to provide localized remappings, which only apply when the referring module matches a specific URL prefix.

For example:. With this import map, the statement import "moment" will have different meanings depending on which referrer script contains the statement:. A typical usage of scopes is to allow multiple versions of the "same" module to exist in a web application, with some parts of the module graph importing one version, and other parts importing another version. Scopes can overlap each other, and overlap the global " imports " specifier map.

At resolution time, scopes are consulted in order of most- to least-specific, where specificity is measured by sorting the scopes using the code unit less than operation.

The child text content of a script element representing an import map must match the following import map authoring requirements :. It must be valid JSON. The values corresponding to the " imports " and " scopes " keys, if present, must themselves be JSON objects. The value corresponding to the " imports " key, if present, must be a valid module specifier map. The value corresponding to the " scopes " key, if present, must be a JSON object, whose keys are valid URL strings and whose values are valid module specifier maps.

A valid module specifier map is a JSON object that meets the following requirements:. All of its keys must be nonempty. All of its values must be strings. imports , a module specifier map ; and scopes , an ordered map of URLs to module specifier maps. A module specifier map is an ordered map whose keys are strings and whose values are either URLs or nulls. An empty import map is an import map with its imports and scopes both being empty maps.

Each Window has an import map , initially an empty import map. Each Window has an import maps allowed boolean, initially true. To disallow further import maps given an environment settings object settingsObject :. Let global be settingsObject 's global object. If global does not implement Window , then return. Set global 's import maps allowed to false. Import maps are currently disallowed once any module loading has started, or once a single import map is loaded.

These restrictions might be lifted in future specification revisions. To parse an import map string , given a string input and a URL baseURL :. Let parsed be the result of parsing a JSON string to an Infra value given input. If parsed is not an ordered map , then throw a TypeError indicating that the top-level value needs to be a JSON object.

Let sortedAndNormalizedImports be an empty ordered map. If parsed [" imports "] exists , then:. If parsed [" imports "] is not an ordered map , then throw a TypeError indicating that the value for the " imports " top-level key needs to be a JSON object. Set sortedAndNormalizedImports to the result of sorting and normalizing a module specifier map given parsed [" imports "] and baseURL. Let sortedAndNormalizedScopes be an empty ordered map. If parsed [" scopes "] exists , then:. If parsed [" scopes "] is not an ordered map , then throw a TypeError indicating that the value for the " scopes " top-level key needs to be a JSON object.

Set sortedAndNormalizedScopes to the result of sorting and normalizing scopes given parsed [" scopes "] and baseURL. If parsed 's keys contains any items besides " imports " or " scopes ", then the user agent should report a warning to the console indicating that an invalid top-level key was present in the import map. This can help detect typos. It is not an error, because that would prevent any future extensions from being added backward-compatibly.

Return an import map whose imports are sortedAndNormalizedImports and whose scopes are sortedAndNormalizedScopes. The import map that results from this parsing algorithm is highly normalized. html , the input.

will generate an import map with imports of. and despite nothing being present in the input string an empty ordered map for its scopes. To sort and normalize a module specifier map , given an ordered map originalMap and a URL baseURL :. Let normalized be an empty ordered map.

Let normalizedSpecifierKey be the result of normalizing a specifier key given specifierKey and baseURL. If normalizedSpecifierKey is null, then continue. If value is not a string , then:.

The user agent may report a warning to the console indicating that addresses need to be strings. Set normalized [ normalizedSpecifierKey ] to null. Let addressURL be the result of resolving a URL-like module specifier given value and baseURL. If addressURL is null, then:. The user agent may report a warning to the console indicating that the address was invalid.

The user agent may report a warning to the console indicating that an invalid address was given for the specifier key specifierKey ; since specifierKey ends with a slash, the address needs to as well. Set normalized [ normalizedSpecifierKey ] to addressURL.

Return the result of sorting in descending order normalized , with an entry a being less than an entry b if a 's key is code unit less than b 's key.

To sort and normalize scopes , given an ordered map originalMap and a URL baseURL :. If potentialSpecifierMap is not an ordered map , then throw a TypeError indicating that the value of the scope with prefix scopePrefix needs to be a JSON object. Let scopePrefixURL be the result of URL parsing scopePrefix with baseURL. If scopePrefixURL is failure, then:. The user agent may report a warning to the console that the scope prefix URL was not parseable.

Let normalizedScopePrefix be the serialization of scopePrefixURL. Set normalized [ normalizedScopePrefix ] to the result of sorting and normalizing a module specifier map given potentialSpecifierMap and baseURL.

To normalize a specifier key , given a string specifierKey and a URL baseURL :. The user agent may report a warning to the console indicating that specifier keys may not be the empty string. Let url be the result of resolving a URL-like module specifier , given specifierKey and baseURL. If url is not null, then return the serialization of url. Return specifierKey. This section defines them for user agent hosts. JavaScript contains an implementation-defined HostEnsureCanAddPrivateElement O abstract operation.

Return NormalCompletion unused. JavaScript private fields can be applied to arbitrary objects. Since this can dramatically complicate implementation for particularly-exotic host objects, the JavaScript language specification provides this hook to allow hosts to reject private fields on objects meeting a host-defined criteria.

In the case of HTML, WindowProxy and Location have complicated semantics — particularly around navigation and security — that make implementation of private field semantics challenging, so our implementation simply rejects those objects. JavaScript contains an implementation-defined HostEnsureCanCompileStrings realm abstract operation.

EnsureCSPDoesNotBlockStringCompilation realm. Let script be the running script. If script is a classic script and script 's muted errors is true, then return.

Let settings object be the current settings object. If script is not null, then set settings object to script 's settings object. If operation is " reject ", then:. Append promise to settings object 's about-to-be-notified rejected promises list. If operation is " handle ", then:. If settings object 's about-to-be-notified rejected promises list contains promise , then remove promise from that list and return.

If settings object 's outstanding rejected promises weak set does not contain promise , then return. Remove promise from settings object 's outstanding rejected promises weak set.

The source of much copied reference material: Paul Vinkenoog Copyright © Firebird Project and all contributing authors, under the Public Documentation License Version 1. Please refer to the License Notice in the Appendix. In , it culminated in a language reference manual, in Russian.

At the instigation of Alexey Kovyazin, a campaign was launched amongst Firebird users world-wide to raise funds to pay for a professional translation into English, from which translations into other languages would proceed under the auspices of the Firebird Documentation Project.

This Firebird SQL Language Reference is the first comprehensive manual to cover all aspects of the query language used by developers to communicate, through their applications, with the Firebird relational database management system.

It has a long history. Firebird conforms closely with international standards for SQL, from data type support, data storage structures, referential integrity mechanisms, to data manipulation capabilities and access privileges.

These are the areas addressed in this volume. The material for assembling this Language Reference has been accumulating in the tribal lore of the open source community of Firebird core developers and user-developers for 15 years. However, it came without rights to existing documentation.

Once the code base had been forked by its owners for private, commercial development, it became clear that the open source, non-commercial Firebird community would never be granted right of use.

The two important books from the InterBase 6 published set were the Data Definition Guide and the Language Reference. The former covered the data definition language DDL subset of the SQL language, while the latter covered most of the rest. Fortunately for Firebird users over the years, both have been easy to find on-line as PDF books. From around , Paul, with Firebird Project lead Dmitry Yemanov and a documenter colleague Thomas Woinke, set about the task of designing and assembling a complete SQL language reference for Firebird.

They began with the material from the LangRef Updates, which is voluminous. It was going to be a big job but, for all concerned, a spare-time one.

They wrote the bulk of the missing DDL section from scratch and wrote, translated or reused DML and PSQL material from the LangRef Updates, Russian language support forums, Firebird release notes, read-me files and other sources.

By the end of , they had the task almost complete, in the form of a Microsoft Word document. The Russian sponsors, recognising that their efforts needed to be shared with the world-wide Firebird community, asked some Project members to initiate a crowd-funding campaign to have the Russian text professionally translated into English.

From there, the source text would be available for translation into other languages for addition to the library. The fund-raising campaign happened at the end of and was successful. In June, , professional translator Dmitry Borodin began translating the Russian text.

Once the DocBook source appears in CVS, we hope the trusty translators will start making versions in German, Japanese, Italian, French, Portuguese, Spanish, Czech. Certainly, we never have enough translators so please, you Firebirders who have English as a second language, do consider translating some sections into your first language. The first full language reference manual for Firebird would not have eventuated without the funding that finally brought it to fruition.

We acknowledge these contributions with gratitude and thank you all for stepping up. Moscow Exchange is the largest exchange holding in Russia and Eastern Europe, founded on December 19, , through the consolidation of the MICEX founded in and RTS founded in exchange groups.

IBSurgeon ibase. ru Russia. Distinct subsets of SQL apply to different sectors of activity. DSQL represents statements passed by client applications through the public Firebird API and processed by the database engine.

Procedural SQL augments Dynamic SQL to allow compound statements containing local variables, assignments, conditions, loops and other procedural constructs. Originally, PSQL extensions were available in persistent stored modules procedures and triggers only, but in more recent releases they were surfaced in Dynamic SQL as well see EXECUTE BLOCK. and preprocess those embedded constructs into the proper Firebird API calls.

Interactive ISQL refers to the language that can be executed using Firebird isql , the command-line application for accessing databases interactively. As a regular client application, its native language is DSQL. It also offers a few additional commands that are not available outside its specific environment. Both DSQL and PSQL subsets are completely presented in this reference.

Neither ESQL nor ISQL flavours are described here unless mentioned explicitly. SQL dialect is a term that defines the specific features of the SQL language that are available when accessing a database. SQL dialects can be defined at the database level and specified at the connection level. Three dialects are available:. Dialect 1 is intended solely to allow backward comptibility with legacy databases from very old InterBase versions, v. Dialect 1 databases retain certain language features that differ from Dialect 3, the default for Firebird databases.

Date and time information are stored in a DATE data type. A TIMESTAMP data type is also available, that is identical to this DATE implementation. Double quotes may be used as an alternative to apostrophes for delimiting string data. Double-quoting strings is therefore to be avoided strenuously. The precision for NUMERIC and DECIMAL data types is smaller than in Dialect 3 and, if the precision of a fixed decimal number is greater than 9, Firebird stores it internally as a long floating point value.

Dialect 2 is available only on the Firebird client connection and cannot be set in the database. It is intended to assist debugging of possible problems with legacy data when migrating a database from dialect 1 to 3. numbers DECIMAL and NUMERIC data types are stored internally as long fixed point values scaled integers when the precision is greater than 9.

Double quotes are reserved for delimiting non-regular identifiers, enabling object names that are case-sensitive or that do not meet the requirements for regular identifiers in other ways. Use of Dialect 3 is strongly recommended for newly developed databases and applications. Both database and connection dialects should match, except under migration conditions with Dialect 2. Processing of every SQL statement either completes successfully or fails due to a specific error condition.

The primary construct in SQL is the statement. A statement defines what the database management system should do with a particular data or metadata object. A clause defines a certain type of directive in a statement. For instance, the WHERE clause in a SELECT statement and in some other data manipulation statements UPDATE, DELETE specifies criteria for searching one or more tables for the rows that are to be selected, updated or deleted.

Options, being the simplest constructs, are specified in association with specific keywords to provide qualification for clause elements. Where alternative options are available, it is usual for one of them to be the default, used if nothing is specified for that option. For instance, the SELECT statement will return all of the rows that match the search criteria unless the DISTINCT option restricts the output to non-duplicated rows.

All words that are included in the SQL lexicon are keywords. Some keywords are reserved , meaning their usage as identifiers for database objects, parameter names or variables is prohibited in some or all contexts.

Non-reserved keywords can be used as identifiers, although it is not recommended. From time to time, non-reserved keywords may become reserved when some new language feature is introduced. For instance, the following statement will be executed without errors because, although ABS is a keyword, it is not a reserved word. On the contrary, the following statement will return an error because ADD is both a keyword and a reserved word.

Refer to the list of reserved words and keywords in the chapter Reserved Words and Keywords. All database objects have names, often called identifiers. Two types of names are valid as identifiers: regular names, similar to variable names in regular programming languages, and delimited names that are specific to SQL. To be valid, each type of identifier must conform to a set of rules, as follows:.

The name must start with an unaccented, 7-bit ASCII alphabetic character. It may be followed by other 7-bit ASCII letters, digits, underscores or dollar signs. No other characters, including spaces, are valid. The name is case-insensitive, meaning it can be declared and used in either upper or lower case. It may contain characters from any Latin character set, including accented characters, spaces and special characters.

Delimited identifiers are available in Dialect 3 only. For more details on dialects, see SQL Dialects. A delimited identifier such as "FULLNAME" is the same as the regular identifiers FULLNAME , fullname , FullName , and so on. The reason is that Firebird stores all regular names in upper case, regardless of how they were defined or declared.

Delimited identifiers are always stored according to the exact case of their definition or declaration. Thus, "FullName" quoted is different from FullName unquoted, i. Literals are used to represent data in a direct format.

Examples of standard types of literals are:. Details about handling the literals for each data type are discussed in the next chapter, Data Types and Subtypes. Some of these characters, alone or in combinations, may be used as operators arithmetical, string, logical , as SQL command separators, to quote identifiers and to mark the limits of string literals or comments.

Comments may be present in SQL scripts, SQL statements and PSQL modules. A comment can be any text specified by the code writer, usually used to document how particular parts of the code work. The parser ignores the text of comments. Text in block comments may be of any length and can occupy multiple lines. In-line comments start with a pair of hyphen characters, -- and continue up to the end of the current line.

define columns in a database table in the CREATE TABLE statement or change columns using ALTER TABLE. declare or change a domain using the CREATE DOMAIN or ALTER DOMAIN statements. declare local variables in stored procedures, PSQL blocks and triggers and specify parameters in stored procedures.

provide arguments for the CAST function when explicitly converting data from one type to another. The size of a BLOB segment is limited to 64K.

Node.js v19.3.0 documentation,Search Results

Websys. addaudithook (hook) ¶ Append the callable hook to the list of active auditing hooks for the current (sub)interpreter.. When an auditing event is raised through the blogger.com() function, each hook will be called in the order it was added with the event name and the tuple of arguments. Native hooks added by PySys_AddAuditHook() are called first, WebBinary Trees are the most commonly used version of trees wherein each node of the tree can have utmost two child nodes. To simplify, each node, including the root node will either have 0, 1 or 2 children, not more or less than that.. A node which has 0 children is called a leaf node. In the above figure; 4, 3, 1, 2 are the leaf nodes as they have no child nodes WebSubtype 0: BINARY. If a subtype is not specified, the specification is assumed to be for untyped data and the default SUB_TYPE 0 is applied. The alias for subtype zero is BINARY. This is the subtype to specify when the data are any form of binary file or stream: images, audio, word-processor files, PDFs and so on. Subtype 1: TEXT Webnode [options] [V8 options] [blogger.com | -e "script" | - ] [arguments] Please see the Command-line options document for more information. Example # An example of a web server written with blogger.com which responds with 'Hello, World!': Commands in this document start with $ or > to replicate how they would appear in a user's terminal Web1 day ago · The following defines the allocation of the agent clusters of all other types of agents.. To obtain a worker/worklet agent, given an environment settings object or null outside settings, a boolean isTopLevel, and a boolean canBlock, run these steps. Let agentCluster be null.; If isTopLevel is true, then. Set agentCluster to a new agent Web26/10/ · Key Findings. California voters have now received their mail ballots, and the November 8 general election has entered its final stage. Amid rising prices and economic uncertainty—as well as deep partisan divisions over social and political issues—Californians are processing a great deal of information to help them choose state constitutional ... read more

PPIC Website Policies Statement Close. The reason for this error handling behavior is that these callbacks are running at potentially volatile points in an object's lifetime, for example during class construction and destruction. exe or dxc. This can be set at build time with the --prefix argument to the configure script. Attempting to import a JavaScript resource using an import statement with a type import assertion will fail:.

The Buffer module pre-allocates an internal Buffer instance of size Buffer. An indicator of the native byte order. JavaScript contains an implementation-defined HostCallJobCallback callbackVtopmost binary options platform, argumentsList abstract operation to let hosts restore state when invoking JavaScript callbacks from inside tasks. Frame N Part MM. Nsight Graphics also supports reading debug info from files that have been generated using the dxc. minimum non-zero value for sys.

Categories: