CREATE CAST

Use the CREATE CAST statement to register a cast that converts data from one data type to another.

Only Dynamic Server supports this statement, which is an extension to the ANSI/ISO standard for SQL.

Syntax

           .-EXPLICIT-.
>>-CREATE--+-IMPLICIT-+--CAST----------------------------------->
 
>--( source_type--AS--target_type--+----------------+--)-------><
                                   '-WITH--function-'

Element	Description	Restrictions	Syntax
function	UDR that you register to implement the cast	See WITH Clause.	Database Object Name
source_type	Data type to be converted	Must exist in the database at the time the cast is registered. See also Source and Target Data Types.	Data Type
target_type	Data type that results from the conversion	The same restrictions that apply for the source_type (as listed above) also apply for the target_type	Data Type

Usage

A cast is a mechanism that the database server uses to convert one data type to another. The database server uses casts to perform the following tasks:

To compare two values in the WHERE clause of a SELECT, UPDATE, or DELETE statement
To pass values as arguments to user-defined routines
To return values from user-defined routines

To create a cast, you must have the necessary privileges on both the source data type and the target data type. All users have access privileges to use the built-in data types. To create a cast to or from an OPAQUE, DISTINCT, or named ROW data type, however, requires the Usage privilege on that data type.

The CREATE CAST statement registers a cast in the syscasts system catalog table. For more information on syscasts, see the chapter on system catalog tables in the IBM Informix Guide to SQL: Reference.