On 2009-04-24, Shawn Tayler <stay...@washoecounty.us> wrote: > Hello, > > I'm doing a quick comparison between a couple tables, trying to cleanup > some inconsistencies, and what should be a simple check between 2 tables > doesn't seem to be working. psql is 8.3.7 and server is 8.2.13. > > I run the following: > > select sfd.lid as sflid,sd.lid as slid,sfd.serial from sfd,shawns_data > sd where sfd.serial = sd.serial_number order by sfd.lid; > > the lid columns in both tables should be identical, but as you see in > this sample, they do differ: > > sflid | slid | serial > -------+-------+---------- > 14056 | 14056 | 9614583 > 14057 | | 9614984 > 14058 | 14058 | 9614737 > 14059 | 14059 | 9614579 > 14060 | | 9614827 > 14061 | 14061 | 9614726 > 14062 | 14062 | 9614966 > 14063 | 14063 | 9615079 > > So running this query: > > select count(*) from sfd,shawns_data sd where sfd.serial = sd.serial_number > and sfd.lid != sd.lid; > > I should show some rows that do not match, at least 2 (there are more than > shown). > > But instead I get this: > > count > ------- > 0 > (1 row) > > > What am I doing wrong?
expecting NULL values not-equal something. select count(*) from sfd,shawns_data sd where sfd.serial = sd.serial_number and COALESCE( sfd.lid != sd.lid, TRUE ) the above include rows where both are NULL, if that's undesirable they must be explicitly excluded. -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
