PostgreSQL Date Check Costraint
create table foo
(
    some_date date not null check (some_date &gt; date '1998-02-01');
);


More details in the manual:


http://www.postgresql.org/docs/current/static/datatype-datetime.html
http://www.postgresql.org/docs/current/static/ddl-constraints.html#DDL-CONSTRAINTS-CHECK-CONSTRAINTS