ALTER DOMAIN

NAME

ALTER DOMAIN - change 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

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 [create_domain(7)]. 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.

You must own the domain to use ALTER DOMAIN; except for ALTER DOMAIN OWNER, which may only be executed by a superuser.

PARAMETERS

name: The name (possibly 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.

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;

COMPATIBILITY

The ALTER DOMAIN statement is compatible with SQL99, except for the OWNER variant, which is a PostgreSQL extension.