ALTER DOMAIN
SQL - Language Statements
ALTER DOMAIN
change the definition of a domain
ALTER DOMAIN
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
.
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.