CAST()

Procedural SQL (PSQL) StatementsAggregate Functions

`CAST()`

Converts a value from one data type to another

Result type

As specified by target_type

Syntax

CAST (<expression> AS <target_type>)

<target_type> ::= <domain_or_non_array_type> | <array_datatype>

<domain_or_non_array_type> ::=
  !! See Scalar Data Types Syntax !!

<array_datatype> ::=
  !! See Array Data Types Syntax !!

Table 1. `CAST` Function Parameters
Parameter	Description
expression	SQL expression
sql_datatype	SQL data type

CAST converts an expression to the desired data type or domain.If the conversion is not possible, an error is raised.

“Shorthand” Syntax

Alternative syntax, supported only when casting a string literal to a DATE, TIME or TIMESTAMP:

datatype 'date/timestring'

This syntax was already available in InterBase, but was never properly documented.In the SQL standard, this feature is called “datetime literals”.

Note	Since Firebird 4.0, the use of `'NOW'`, `'YESTERDAY'` and `'TOMORROW'` in the shorthand cast is no longer allowed;only literals defining a fixed moment in time are supported.