Unique constraint

Posted in 1999

Topics: SQL Development & Query Writing, Triggers, Constraints & Referential Integrity

Luse Harold — Thu, 16 Sep 1999 12:45:51 -0600 (MDT) — source: Informix-list mailing list archive (1991-1998)

Is there any advantage to putting a unique constraint on a column instead of creating a unique index on a column? I have seen this done, and I don't see any advantage. The column is being used in a join anyway, so it would seem that a unique index would be the way to go. Comments anyone? ==================================================================== Harold Luse Phone: (970) 491-4120 Veterinary Teaching Hospital Fax: (970) 491-4123 Colorado State University Pager: (970) 229-8173 Fort Collins, Colorado USA E-mail: hluse@vth.colostate.edu ====================================================================

↪ replying to Luse Harold

Art S. Kagel — Fri, 17 Sep 1999 11:48:13 -0400 — source: Informix-list mailing list archive (1991-1998)

Luse Harold wrote: > > Is there any advantage to putting a unique constraint on a column instead > of creating a unique index on a column? I have seen this done, and I > don't see any advantage. The column is being used in a join anyway, so it > would seem that a unique index would be the way to go. > > Comments anyone? Does not matter either way. It is a documentation thing. The UNIQUE CONSTRAINT will create the same UNIQUE index you would and that index alone will be used to guarantee uniqueness of rows. Art S. Kagel