ALTER DOMAIN

Changes the definition of a domain.

Synopsis

ALTER DOMAIN <name> { SET DEFAULT <expression> | DROP DEFAULT }

ALTER DOMAIN <name> { SET | DROP } NOT NULL

ALTER DOMAIN <name> ADD <domain_constraint>

ALTER DOMAIN <name> DROP CONSTRAINT <constraint_name> [RESTRICT | CASCADE]

ALTER DOMAIN <name> OWNER TO <new_owner>

ALTER DOMAIN <name> SET SCHEMA <new_schema>

Description

ALTER DOMAIN changes the definition of an existing domain. There are several sub-forms:

SET/DROP DEFAULT — These forms set or remove the default value for a domain. Note that defaults only apply to subsequent INSERT commands. They do not affect rows already in a table using the domain.
SET/DROP NOT NULL — These forms change whether a domain is marked to allow NULL values or to reject NULL values. You may only SET NOT NULL when the columns using the domain contain no null values.
ADD domain_constraint — This form adds a new constraint to a domain using the same syntax as CREATE DOMAIN. This will only succeed if all columns using the domain satisfy the new constraint.
DROP CONSTRAINT — This form drops constraints on a domain.
OWNER — This form changes the owner of the domain to the specified user.
SET SCHEMA — This form changes the schema of the domain. Any constraints associated with the domain are moved into the new schema as well.

You must own the domain to use ALTER DOMAIN. To change the schema of a domain, you must also have CREATE privilege on the new schema. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the domain's schema. (These restrictions enforce that altering the owner does not do anything you could not do by dropping and recreating the domain. However, a superuser can alter ownership of any domain anyway.)

Parameters

name: The name (optionally schema-qualified) of an existing domain to alter.
domain_constraint: New domain constraint for the domain.
constraint_name: Name of an existing constraint to drop.
CASCADE: Automatically drop objects that depend on the constraint.
RESTRICT: Refuse to drop the constraint if there are any dependent objects. This is the default behavior.
new_owner: The user name of the new owner of the domain.
new_schema: The new schema for the domain.

Examples

To add a NOT NULL constraint to a domain:

ALTER DOMAIN zipcode SET NOT NULL;

To remove a NOT NULL constraint from a domain:

ALTER DOMAIN zipcode DROP NOT NULL;

To add a check constraint to a domain:

ALTER DOMAIN zipcode ADD CONSTRAINT zipchk CHECK 
(char_length(VALUE) = 5);

To remove a check constraint from a domain:

ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;

To move the domain into a different schema:

ALTER DOMAIN zipcode SET SCHEMA customers;

Compatibility

ALTER DOMAIN conforms to the SQL standard, except for the OWNER and SET SCHEMA variants, which are Greenplum Database extensions.