PROTECTED]
Subject: Re: user defined table constraint
You need to use a UNIQUE index:
ALTER TABLE table ADD UNIQUE user_id_primary (user_id, is_primary);
I can't find a specific section about UNIQUE indexes in the mysql
docs, but I'm sure it's there and I'm pretty sure the syntax about is
correct
That depends, can the user have more than 2 records? as in only 1 yes
record and 1 no record? If that were the case you could create a unique
index on (user_id, is_primary). However, I suspect that is not the case.
If I remember my M$ $QL correctly, User Constraints are evaluated during
INSERT
Excuse me for top-posting but Outlook Express won't put revision bars in
front of your original remarks and I'm too lazy to type them all in myself
;-)
Anyway, if you define one of your columns, such as user_id as a primary key,
you can be sure that there will never be two rows with the same
