The Firebird 5.0 Language Reference | Bitwise Functions

`BIN_SHL()`

Bitwise left-shift

Result type

BIGINT or INT128 depending on the first argument

Syntax

BIN_SHL (number, shift)

Table 1. `BIN_SHL` Function Parameters
Parameter	Description
number	A number of an integer type
shift	The number of bits the number value is shifted by

Returns the first argument bitwise left-shifted by the second argument, i.e. a << b or a·2^b.

See also

[fblangref50-scalarfuncs-bin-shr]

`BIN_SHR()`

Bitwise right-shift with sign extension

Result type

BIGINT or INT128 depending on the first argument

Syntax

BIN_SHR (number, shift)

Table 1. `BIN_SHR` Function Parameters
Parameter	Description
number	A number of an integer type
shift	The number of bits the number value is shifted by

Returns the first argument bitwise right-shifted by the second argument, i.e. a >> b or a/2^b.

The operation performed is an arithmetic right shift (x86 SAR), meaning that the sign of the first operand is always preserved.

See also

[fblangref50-scalarfuncs-bin-shl]

`BIN_XOR()`

Bitwise XOR

Result type

integer type (the widest type of the arguments)

Note	`SMALLINT` result is returned only if all the arguments are explicit `SMALLINT`s or `NUMERIC(n, 0)` with n <= 4;otherwise small integers return an `INTEGER` result.

Syntax

BIN_XOR (number, number [, number ...])

Table 1. `BIN_XOR` Function Parameters
Parameter	Description
number	A number of an integer type

Returns the result of the bitwise XOR operation on the argument(s).

UUID Functions

`CHAR_TO_UUID()`

Converts a string UUID to its binary representation

Result type

BINARY(16)

Syntax

CHAR_TO_UUID (ascii_uuid)

Table 1. `CHAR_TO_UUID` Function Parameter
Parameter	Description
ascii_uuid	A 36-character representation of UUID.‘`-`’ (hyphen) in positions 9, 14, 19 and 24;valid hexadecimal digits in any other positions, e.g. 'A0bF4E45-3029-2a44-D493-4998c9b439A3'

Converts a human-readable 36-char UUID string to the corresponding 16-byte UUID.

`CHAR_TO_UUID` Examples

select char_to_uuid('A0bF4E45-3029-2a44-D493-4998c9b439A3') from rdb$database
-- returns A0BF4E4530292A44D4934998C9B439A3 (16-byte string)

select char_to_uuid('A0bF4E45-3029-2A44-X493-4998c9b439A3') from rdb$database
-- error: -Human readable UUID argument for CHAR_TO_UUID must
--         have hex digit at position 20 instead of "X (ASCII 88)"

`GEN_UUID()`

Generates a random binary UUID

Result type

BINARY(16)

Syntax

GEN_UUID ()

Returns a universally unique ID as a 16-byte character string.

`GEN_UUID` Example

select gen_uuid() from rdb$database
-- returns e.g. 017347BFE212B2479C00FA4323B36320 (16-byte string)

`UUID_TO_CHAR()`

Converts a binary UUID to its string representation

Result type

CHAR(36)

Syntax

UUID_TO_CHAR (uuid)

Table 1. `UUID_TO_CHAR` Function Parameters
Parameter	Description
uuid	16-byte UUID

Converts a 16-byte UUID to its 36-character, human-readable ASCII representation.

`UUID_TO_CHAR` Examples

select uuid_to_char(x'876C45F4569B320DBCB4735AC3509E5F') from rdb$database
-- returns '876C45F4-569B-320D-BCB4-735AC3509E5F'

select uuid_to_char(gen_uuid()) from rdb$database
-- returns e.g. '680D946B-45FF-DB4E-B103-BB5711529B86'

select uuid_to_char('Firebird swings!') from rdb$database
-- returns '46697265-6269-7264-2073-77696E677321'

Functions for Sequences (Generators)

`GEN_ID()`

Increments a sequence (generator) value and returns its new value

Result type

BIGINT — dialect 2 and 3
INTEGER — dialect 1

Syntax

GEN_ID (generator-name, step)

Table 1. `GEN_ID` Function Parameters
Parameter	Description
generator-name	Identifier name of a generator (sequence)
step	An integer expression of the increment

If step equals 0, the function will leave the value of the generator unchanged and return its current value.

The SQL-compliant NEXT VALUE FOR syntax is preferred, except when an increment other than the configured increment of the sequence is needed.

Warning

If the value of the step parameter is less than zero, it will decrease the value of the generator.You should be cautious with such manipulations in the database, as they could compromise data integrity (meaning, subsequent insert statements could fail due to generating of duplicate id values).

Note	In dialect 1, the result type is `INTEGER`, in dialect 2 and 3 it is `BIGINT`.

`GEN_ID` Example

new.rec_id = gen_id(gen_recnum, 1);

Conditional Functions

`COALESCE()`

Returns the first non-NULL argument

Result type

Depends on input

Syntax

COALESCE (<exp1>, <exp2> [, <expN> ... ])

Table 1. `COALESCE` Function Parameters
Parameter	Description
exp1, exp2 … expN	A list of expressions of compatible types

The COALESCE function takes two or more arguments and returns the value of the first non-NULL argument.If all the arguments evaluate to NULL, the result is NULL.

`COALESCE` Examples

This example picks the Nickname from the Persons table.If it happens to be NULL, it goes on to FirstName.If that too is NULL, “'Mr./Mrs.'” is used.Finally, it adds the family name.All in all, it tries to use the available data to compose a full name that is as informal as possible.This scheme only works if absent nicknames and first names are NULL: if one of them is an empty string, COALESCE will happily return that to the caller.That problem can be fixed by using [fblangref50-scalarfuncs-nullif].

select
  coalesce (Nickname, FirstName, 'Mr./Mrs.') || ' ' || LastName
    as FullName
from Persons

`DECODE()`

Shorthand “simple CASE”-equivalent function

Result type

Depends on input

Syntax

DECODE(<testexpr>,
  <expr1>, <result1>
  [<expr2>, <result2> ...]
  [, <defaultresult>])

Table 1. `DECODE` Function Parameters
Parameter	Description
testexpr	An expression of any compatible type that is compared to the expressions expr1, expr2 … exprN
expr1, expr2, … exprN	Expressions of any compatible types, to which the testexpr expression is compared
result1, result2, … resultN	Returned values of any type
defaultresult	The expression to be returned if none of the conditions is met

DECODE is a shorthand for the so-called “simple CASE” construct, in which a given expression is compared to a number of other expressions until a match is found.The result is determined by the value listed after the matching expression.If no match is found, the default result is returned, if present, otherwise NULL is returned.

The equivalent CASE construct:

CASE <testexpr>
  WHEN <expr1> THEN <result1>
  [WHEN <expr2> THEN <result2> ...]
  [ELSE <defaultresult>]
END

Caution

Matching is done with the ‘=’ operator, so if testexpr is NULL, it won’t match any of the exprs, not even those that are NULL.

`DECODE` Examples

select name,
  age,
  decode(upper(sex),
         'M', 'Male',
         'F', 'Female',
         'Unknown'),
  religion
from people

See also

CASE, Simple CASE

`IIF()`

Ternary conditional function

Result type

Depends on input

Syntax

IIF (<condition>, ResultT, ResultF)

Table 1. `IIF` Function Parameters
Parameter	Description
condition	A true\|false expression
resultT	The value returned if the condition is true
resultF	The value returned if the condition is false

IIF takes three arguments.If the first evaluates to true, the second argument is returned;otherwise the third is returned.

IIF could be likened to the ternary “<condition> ? resultT : resultF” operator in C-like languages.

Note	`IIF(<condition>, resultT, resultF)` is a shorthand for “`CASE WHEN <condition> THEN resultT ELSE resultF END`”.

`IIF` Examples

select iif( sex = 'M', 'Sir', 'Madam' ) from Customers

`MAXVALUE()`

Returns the maximum value of its arguments

Result type

Varies according to input — result will be of the same data type as the first expression in the list (expr1).

Syntax

MAXVALUE (<expr1> [, ... , <exprN> ])

Table 1. `MAXVALUE` Function Parameters
Parameter	Description
expr1 … exprN	List of expressions of compatible types

Returns the maximum value from a list of numerical, string, or date/time expressions.This function fully supports text BLOBs of any length and character set.

If one or more expressions resolve to NULL, MAXVALUE returns NULL.This behaviour differs from the aggregate function MAX.

`MAXVALUE` Examples

SELECT MAXVALUE(PRICE_1, PRICE_2) AS PRICE
  FROM PRICELIST

See also

[fblangref50-scalarfuncs-minvalue]

`MINVALUE()`

Returns the minimum value of its arguments

Result type

Varies according to input — result will be of the same data type as the first expression in the list (expr1).

Syntax

MINVALUE (<expr1> [, ... , <exprN> ])

Table 1. `MINVALUE` Function Parameters
Parameter	Description
expr1 … exprN	List of expressions of compatible types

Returns the minimum value from a list of numerical, string, or date/time expressions.This function fully supports text BLOBs of any length and character set.

If one or more expressions resolve to NULL, MINVALUE returns NULL.This behaviour differs from the aggregate function MIN.

`MINVALUE` Examples

SELECT MINVALUE(PRICE_1, PRICE_2) AS PRICE
  FROM PRICELIST

See also

[fblangref50-scalarfuncs-maxvalue]

`NULLIF()`

Conditional NULL function

Result type

Depends on input

Syntax

NULLIF (<exp1>, <exp2>)

Table 1. `NULLIF` Function Parameters
Parameter	Description
exp1	An expression
exp2	Another expression of a data type compatible with exp1

NULLIF returns the value of the first argument, unless it is equal to the second.In that case, NULL is returned.

`NULLIF` Example

select avg( nullif(Weight, -1) ) from FatPeople

This will return the average weight of the persons listed in FatPeople, excluding those having a weight of -1, since AVG skips NULL data.Presumably, -1 indicates “weight unknown” in this table.A plain AVG(Weight) would include the -1 weights, thus skewing the result.

BIN_SHL()

BIN_SHL()

BIN_SHR()

BIN_XOR()

UUID Functions

CHAR_TO_UUID()

CHAR_TO_UUID Examples

GEN_UUID()

GEN_UUID Example

UUID_TO_CHAR()

UUID_TO_CHAR Examples

Functions for Sequences (Generators)

GEN_ID()

GEN_ID Example

Conditional Functions

COALESCE()

COALESCE Examples

DECODE()

DECODE Examples

IIF()

IIF Examples

MAXVALUE()

MAXVALUE Examples

MINVALUE()

MINVALUE Examples

NULLIF()

NULLIF Example

`BIN_SHL()`

`BIN_SHR()`

`BIN_XOR()`

`CHAR_TO_UUID()`

`CHAR_TO_UUID` Examples

`GEN_UUID()`

`GEN_UUID` Example

`UUID_TO_CHAR()`

`UUID_TO_CHAR` Examples

`GEN_ID()`

`GEN_ID` Example

`COALESCE()`

`COALESCE` Examples

`DECODE()`

`DECODE` Examples

`IIF()`

`IIF` Examples

`MAXVALUE()`

`MAXVALUE` Examples

`MINVALUE()`

`MINVALUE` Examples

`NULLIF()`

`NULLIF` Example