??? wrote: > I want detail usage introduction about constraint,such as how > to constrain a string to be exactly 4 character and start with 'z'. > Where can I find the reference of CHECK? detail usage. Documentation: http://www.postgresql.org/docs/current/static/ddl-constraints.html#AEN2254 The check you want would look similar to this: CHECK (length(val) = 4 AND substr(val, 1, 1) = 'z') Yours, Laurenz Albe -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
