Re: [SQL] Newbie questions

At 10:26 +0200 on 14/12/98, Remigiusz Sokolowski wrote:

> > select * from animals where id='dogs' ignore case;
>
> look at operators in docs
> ~~ - LIKE operator
> ~* - match(regex), case insensitive operator
> I have no idea which is better
> Rem
> p.s. I could make some mistakes in this examples - check in amnual or docs

The like and regexp do a match rather than an equality test.

For an exact equality ignoring case, simply use

SELECT *
FROM animals
WHERE lower( id ) = 'dogs';

Note that this means an index on the id column will NOT be used, because
each value has to be converted to lower before testing. When I needed this
to be an indexed search, I added a column, called, say "lower_id", which
contains the lowercase version of the value in the "id" column. Then I
indexed that column and then you can ask WHERE lower_id = 'dogs' and get a
fast answer.

There is also the possibility of creating a functional index, but I haven't
managed to cause this sort of index to "kick in" on my version of postgres
(6.2.1).

Herouth

--
Herouth Maoz, Internet developer.
Open University of Israel - Telem project
http://telem.openu.ac.il/~herutma