CREATE DOMAIN
Synopsis
Use the CREATE DOMAIN statement to create a user-defined data type with optional constraints, such as range of valid values, DEFAULT, NOT NULL, and CHECK. Domains are useful to abstract data types with common constraints. For example, domain can be used to represent phone number columns that will require the same CHECK constraints on the syntax.
Syntax
create_domain ::= CREATE DOMAIN name [ AS ] data_type
[ DEFAULT expression ]
[ [ domain_constraint [ ... ] ] ]
domain_constraint ::= [ CONSTRAINT constraint_name ]
{ NOT NULL | NULL | CHECK ( expression ) }
create_domain
domain_constraint
Semantics
create_domain
CREATE DOMAIN name
Specify the name of the domain. An error is raised if name already exists in the specified database.
AS data_type
Specify the underlying data type.
DEFAULT expression
Set the default value for columns of the domain data type.
domain_constraint
CONSTRAINT constraint_name
Specify the optional name for the constraint.
NOT NULL
Do not allow null values.
NULL
Allow null values (default).
CHECK ( expression )
Enforce a constraint that the values of the domain must satisfy and returns a Boolean value.
The key word VALUE should be used to refer to the value being tested. Expressions evaluating to TRUE or UNKNOWN succeed.
Examples
yugabyte=# CREATE DOMAIN phone_number AS TEXT CHECK(VALUE ~ '^\d{3}-\d{3}-\d{4}$');
yugabyte=# CREATE TABLE person(first_name TEXT, last_name TEXT, phone_number phone_number);