search engine php3 not case sensitive

hi all
I hope this is not a trivial question... I haven't find any answer on
the FAQ anyway...
I'm developing a little search engine (PostgreSQL+Apache+PHP3) working
wiht long fields (like 8000 char)
if someone insert the word
<word>
into my form I can search for:
<word> "as is"
Word
WORD
word

If someone would search for a chemical formula I should provide the
right output without any dependencies with the upper case or lower case
used by the client...
for example if you write
nacl
I should be able to search for
<nacl> "as is"
Nacl
NACL
Nacl

BUT most of all for NaCl, the right one!
Real search engine like Altavista to that of course... I don't assume I
want to develop something like Altavista, for sure ;P, but a little hand
could be appreciated anyway.

thanks.

ps: by the way... the php3 function soundex probably it's not the last
answer on that problem.

--
Carlo Perassi
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