ALTER DOMAIN SQL - Language Statements ALTER DOMAIN change the definition of a table 2002-11-27 ALTER DOMAIN domain { SET DEFAULT value | DROP DEFAULT } ALTER DOMAIN domain { SET | DROP } NOT NULL ALTER DOMAIN domain ADD domain_constraint ALTER DOMAIN domain DROP CONSTRAINT constraint_name [ RESTRICT | CASCADE ] 2002-11-27 domain 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 constraint. RESTRICT Refuse to drop the constraint if there are any dependent objects. This is the default behavior. 1998-04-15 ALTER DOMAIN Message returned from domain alteration. ERROR Message returned if domain is not available. 2002-11-27 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 column. Note that defaults only apply to subsequent INSERT commands; they do not cause 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 tables using the domain contain no null values in the domain based column. ADD domain_constraint This form adds a new constraint to a table using the same syntax as . DROP CONSTRAINT This form drops constraints on a domain. You must own the domain to use ALTER DOMAIN; except for ALTER TABLE OWNER, which may only be executed by a superuser. To add a NOT NULL constraint to a column: ALTER DOMAIN zipcode SET NOT NULL; To remove a NOT NULL constraint from a column: ALTER DOMAIN zipcode DROP NOT NULL; To add a check constraint to a table: ALTER DOMAIN zipcode ADD CONSTRAINT zipchk CHECK (char_length(VALUE) = 5); To remove a check constraint from a table and all its children: ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;