In article <iqne7u$ssa$2...@reversiblemaps.ath.cx>, Jasen Betts <ja...@xnet.co.nz> writes:
> On 2011-05-14, Seb <splu...@gmail.com> wrote: >> Hi, >> >> This probably reflects my confusion with how self joins work. >> >> Suppose we have this table: >> If I want to get a table with records where none of the values in column >> b are found in column a, I thought this should do it: > use the "NOT IN" operator with a subquery to retch the disallowed > values. > select * from tmp where a NOT IN (select b from tmp); The third way is an OUTER JOIN: SELECT t1.a, t1.b FROM tmp t1 LEFT JOIN tmp t2 ON t2.b = t1.a WHERE t2.b IS NULL; -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
