CREATE DOMAIN Statement

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Syntax

CREATE { DOMAIN | DATATYPE } domain-name data-type
   … [ NOT ] NULL ]
   … [ DEFAULT default-value ]

default-value - (back to Syntax)
   special-value 
   | string 
   | global variable 
   | [ - ] number 
   | ( constant-expression ) 
   | built-in-function( constant-expression ) 
   | AUTOINCREMENT 
   | CURRENT DATABASE 
   | CURRENT REMOTE USER 
   | NULL 
   | TIMESTAMP 
   | LAST USER

special-value (back to default-value)
   CURRENT 
      { DATE 
         | TIME 
         | TIMESTAMP 
         | USER 
         | PUBLISHER } 
      | USER

Parameters

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data-type – built-in data type, with precision and scale

Examples

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Example 1 – create a data type named address, which holds a 35-character string, and which may be NULL:
```
CREATE DOMAIN address CHAR( 35 ) NULL
```

Usage

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User-defined data types are aliases for built-in data types, including precision and scale values, where applicable. They improve convenience and encourage consistency in the database.

Note: Use CREATE DOMAIN, rather than CREATE DATATYPE, as CREATE DOMAIN is the ANSI/ISO SQL3 term.

The user who creates a data type is automatically made the owner of that data type. No owner can be specified in the CREATE DATATYPE statement. The user-defined data type name must be unique, and all users can access the data type without using the owner as prefix.

User-defined data types are objects within the database. Their names must conform to the rules for identifiers. User-defined data type names are always case-insensitive, as are built-in data type names.

By default, user-defined data types allow NULLs unless the allow_nulls_by_default database option is set to OFF. In this case, new user-defined data types by default do not allow NULLs. The nullability of a column created on a user-defined data type depends on the setting of the definition of the user-defined data type, not on the setting of the allow_nulls_by_default option when the column is referenced. Any explicit setting of NULL or NOT NULL in the column definition overrides the user-defined data type setting.

The CREATE DOMAIN statement allows you to specify DEFAULT values on user-defined data types. The DEFAULT value specification is inherited by any column defined on the data type. Any DEFAULT value explicitly specified on the column overrides that specified for the data type.

The CREATE DOMAIN statement lets you incorporate a rule, called a CHECK condition, into the definition of a user-defined data type.

SAP Sybase IQ enforces CHECK constraints for base, global temporary. local temporary tables, and user-defined data types.

To drop the data type from the database, use the DROP statement. You must be either the owner of the data type or have the CREATE DATATYPE or CREATE ANY OBJECT system privilege in order to drop a user-defined data type.

Side effects:

Automatic commit

Standards

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SQL—ISO/ANSI SQL compliant.
SAP Sybase Database product—Not supported by Adaptive Server. Transact-SQL provides similar functionality using the sp_addtype system procedure and the CREATE DEFAULT and CREATE RULE statements.

Permissions

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Requires one of:

CREATE DATATYPE system privilege.
CREATE ANY OBJECT system privilege.