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Who Can Create a Domain

The CREATE DOMAIN statement can be executed by:

CREATE DOMAIN Examples

  1. Creating a domain that can take values greater than 1,000, with a default value of 10,000.

    CREATE DOMAIN CUSTNO AS
      INTEGER DEFAULT 10000
      CHECK (VALUE > 1000);
  2. Creating a domain that can take the values 'Yes' and 'No' in the default character set specified during the creation of the database.

    CREATE DOMAIN D_BOOLEAN AS
      CHAR(3) CHECK (VALUE IN ('Yes', 'No'));
  3. Creating a domain with the UTF8 character set and the UNICODE_CI_AI collation.

    CREATE DOMAIN FIRSTNAME AS
      VARCHAR(30) CHARACTER SET UTF8
      COLLATE UNICODE_CI_AI;
  4. Creating a domain of the DATE type that will not accept NULL and uses the current date as the default value.

    CREATE DOMAIN D_DATE AS
      DATE DEFAULT CURRENT_DATE
      NOT NULL;
  5. Creating a domain defined as an array of 2 elements of the NUMERIC(18, 3) type.The starting array index is 1.

    CREATE DOMAIN D_POINT AS
      NUMERIC(18, 3) [2];
    Note

    Domains defined over an array type may be used only to define table columns.You cannot use array domains to define local variables in PSQL modules.

  6. Creating a domain whose elements can be only country codes defined in the COUNTRY table.

    CREATE DOMAIN D_COUNTRYCODE AS CHAR(3)
      CHECK (EXISTS(SELECT * FROM COUNTRY
             WHERE COUNTRYCODE = VALUE));
    Note

    The example is given only to show the possibility of using predicates with queries in the domain test condition.It is not recommended to create this style of domain in practice unless the lookup table contains data that are never deleted.