On Fri, Jul 23, 2010 at 6:17 PM, Alban Hertroys <dal...@solfertje.student.utwente.nl> wrote: >> I thought to do >> >> select * from coloursample where colour & 10 = 10; >> >> ...but that's not right, because it finds the third record is a match. > > > What's not entirely clear to me is whether you only want to find colours that > have BOTH Yellow and Orange set and nothing else, or colours that have EITHER > Yellow and Orange set and nothing else. > > The first case has been answered by Stephen (use a straight 'equals'). The > other case is a bit more complicated. > > That 11 matches using "& 10" is because you filtered out all the other bits > in your comparison by anding them with '0', while they /are/ relevant: they > aren't allowed to be '1' after all. You probably need to look at the inverted > versions of these numbers to get what you need. > > My bit-foo is a bit rusty,
Hehe. Mine too, it would seem! >but this looks like what you need (I used bit-strings for my own convenience): > > development=> select (~ '01010'::bit(5)) | '01010'::bit(5) = '11111'::bit(5); > ?column? > ---------- > t > (1 row) > > development=> select (~ '01011'::bit(5)) | '01010'::bit(5) = '11111'::bit(5); > ?column? > ---------- > f > (1 row) > > development=> select (~ '01110'::bit(5)) | '01010'::bit(5) = '11111'::bit(5); > ?column? > ---------- > f > (1 row) > > development=> select (~ '11010'::bit(5)) | '01010'::bit(5) = '11111'::bit(5); > ?column? > ---------- > f > (1 row) > > development=> select (~ '00010'::bit(5)) | '01010'::bit(5) = '11111'::bit(5); > ?column? > ---------- > t > (1 row) > > development=> select (~ '01000'::bit(5)) | '01010'::bit(5) = '11111'::bit(5); > ?column? > ---------- > t > (1 row) > > > Alban Hertroys Thanks Alban. Steve, too, has joined in again above: the bit-wise OR, together with an equality test on the stored value, would seem to be what's called for. Appreciate the contribution. I think we can all go home now!! :-) Regards HJR -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
