Thank you. I see my mistake now. Shawn M. Downey MPR Associates 632 Plank Road, Suite 110 Clifton Park, NY 12065 518-371-3983 x3 (work) 860-508-5015 (cell)
-----Original Message----- From: D. Richard Hipp [mailto:[EMAIL PROTECTED] Sent: Thursday, October 28, 2004 9:09 AM To: [EMAIL PROTECTED] Subject: Re: [sqlite] How are NULL values deleted? Downey, Shawn wrote: > Does the following schema: > > create table t(col1 text NOT NULL, > col2 text NOT NULL, > col3 text NOT NULL, > UNIQUE(col1,col2), > PRIMARY KEY(col1,col2)); > > State that the COMBINATION of col1+col2 must be unique? Or that BOTH > col1 and col2 must be unique? I assumed the first but I am getting for > rejections for "uniqueness constraint failed" using sqlite 2.8.0. > PRIMARY KEY implies UNIQUE and NOT NULL. So your specification is redundant. Furthermore, a bug in SQLite causes multiple identical indices to be created if you use both UNIQUE and PRIMARY KEY on the same columns. You'll still get the right answers, but your database file will be larger and updates will be slower. The combination of col1+col2 must be unique. This works. Example: [EMAIL PROTECTED] drh]$ sqlite :memory: SQLite version 2.8.15 Enter ".help" for instructions sqlite> create table t(a,b,c,primary key(a,b)); sqlite> insert into t values(1,2,3); sqlite> insert into t values(1,3,4); sqlite> insert into t values(3,2,4); sqlite> insert into t values(1,2,4); SQL error: columns a, b are not unique sqlite> -- D. Richard Hipp -- [EMAIL PROTECTED] -- 704.948.4565
