On Tue, 29 Jun 2004, Stefan Weiss wrote: > On Tuesday, 29 June 2004 00:17, Dmitri Bichko wrote: > > As far as TRUE and FALSE go, from what I know you can use = to compare > > them with boolean columns, unless I misunderstood your question. > > Sorry, I must have remembered that incorrectly, or maybe I've been > thinking of a different DBMS or version. "table.col = TRUE" seems to > work fine for me now. > > I understand that the result of "(anything) = NULL" will always NULL, > so it's a waste of breath. That's where the "IS" operator(?) comes in, > which allows for comparison with NULL. The only question left is why > "IS" can also be used to compare with the TRUE/FALSE keywords (when a > simple "=" should be sufficient here), but not to compare two boolean > columns.
IS TRUE and IS FALSE have a different effect from =true and =false when the left hand side is NULL. The former will return false, the latter will return NULL. ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html