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);

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'));

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;

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;

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];

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));

Changing the data type to INTEGER and setting or changing the default value to 2,000:

ALTER DOMAIN CUSTNO
  TYPE INTEGER
  SET DEFAULT 2000;

Renaming a domain.

ALTER DOMAIN D_BOOLEAN TO D_BOOL;

Deleting the default value and adding a constraint for the domain:

ALTER DOMAIN D_DATE
  DROP DEFAULT
  ADD CONSTRAINT CHECK (VALUE >= date '01.01.2000');

Changing the CHECK constraint:

ALTER DOMAIN D_DATE
  DROP CONSTRAINT;

ALTER DOMAIN D_DATE
  ADD CONSTRAINT CHECK
    (VALUE BETWEEN date '01.01.1900' AND date '31.12.2100');

Changing the data type to increase the permitted number of characters:

ALTER DOMAIN FIRSTNAME
  TYPE VARCHAR(50) CHARACTER SET UTF8;

Adding a NOT NULL constraint:

ALTER DOMAIN FIRSTNAME
  SET NOT NULL;

Removing a NOT NULL constraint:

ALTER DOMAIN FIRSTNAME
  DROP NOT NULL;