Provides a default value for a domain.

    You can use any value expression including subqueries,
    conditional, character, date/time, and numeric expressions as
    default values. See Value Expressions for more information about
    value expressions.

    For more information about NULL, see the NULL_Keyword HELP topic.

    The value expressions described in Value Expressions include
    DBKEY and aggregate functions. However, the DEFAULT clause is
    not a valid location for referencing a DBKEY or an aggregate
    function. If you attempt to reference either, you receive a
    compile-time error.

    If you do not specify a DEFAULT for a column, it inherits the
    DEFAULT from the domain. If you do not specify a default for
    either the column or domain, SQL assigns NULL as the default
    value.