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Re: [PHP] Case Insensitive Searching?

From: Ernest E Vogelsinger <ernest(at)vogelsinger(dot)at>
To: <bcschnei(at)attbi(dot)com>
Cc: <pgsql-novice(at)postgresql(dot)org>, <pgsql-php(at)postgresql(dot)org>
Subject: Re: [PHP] Case Insensitive Searching?
Date: 2003-05-25 19:51:22
Message-ID: 5.1.1.6.2.20030525214642.03109ca8@mail.vogelsinger.at (view raw or flat)
Thread:
Lists: pgsql-novicepgsql-php
At 22:24 23.05.2003, Ben Schneider said:
--------------------[snip]-------------------- 
>I am working on a project where I am creating a PHP front end to a
>Postgres database. The schema is new but the data is old. Meaning I had to
>convert the data from the old Informix DB.
>
>Anyway all of the existing data is in all upper case. However new data
>going in will be in both upper and lower case.(As requested by the customer.)
>
>So the question is, how do I perform a case insensitive search? Is there a
>DB setting I can set to ignore the case?
>
>If not, then an example of some PHP code that can do this would be of a
>great help.
--------------------[snip]-------------------- 

There are a couple of ways to do that, it depends on your likes/dislikes as
well as on performance in your specific case.

You could simply use lower() or upper() in your query constraints:
    .... WHERE lower(column_name) = lower('search_value')

Use the ILIKE operator (case insensitive LIKE):
    .... WHERE column_name ILIKE '%search_value%'

However I did some timings and noticed that ILIKE is appox. 10 times slower
than LIKE. Maybe a problem on my side, but... LIKE constructs usually tend
to NOT use indexes.

To have an index at hand for a lower() search, create an index using
lower() values:
    CREATE INDEX id_lower_content ON mytable(lower(column_name))


-- 
   >O     Ernest E. Vogelsinger
   (\)    ICQ #13394035
    ^     http://www.vogelsinger.at/



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