On 9/17/2010 10:12 AM, Michael Bayer wrote:
On Sep 17, 2010, at 10:58 AM, Michael Bayer wrote:
On Sep 17, 2010, at 9:14 AM, Michael Hipp wrote:
On 9/14/2010 2:23 PM, Michael Hipp wrote:
Is it possible to use a regexp in a like() clause? Or some other way to achieve
something similar?
Can anyone suggest an approach to search a field with a regexp?
if you were using Postgresql, you could use somecolumn.op("~")(someregexp)
http://www.postgresql.org/docs/8.4/interactive/functions-matching.html#FUNCTIONS-POSIX-REGEXP
cant speak for other platforms though you'd have to consult their documentation.
PG also supports MATCH since I see we have some unit tests for that, i.e. column.match(other). I'm not
seeing offhand in PG's docs what it interprets the "MATCH" operator as, i.e. is it a "~",
"SIMILAR TO", not sure.
I guess the reasons I've never had interest in regexp matching in databases are:
1. its always bad to search through tables without being able to use indexes
2. if you're needing to dig into text, it suggests the atoms of that text
should be represented individually in their own column (i.e. normalize)
3. no really, I'm doing flat out full text searching on documents and don't
want to reinvent. Well then I'd use a full blown text extension
(http://www.postgresql.org/docs/8.3/static/textsearch.html) or a separate
search engine.
Thanks for the good suggestions on this. My need is pretty simple. I have a
column that contains values like this:
A100
AA309
B101
I need something to find all the rows that look like Axxx while excluding those
that look like AAxxx. The LIKE operator doesn't seem to be able to do that. I
am using PostgreSQL so the ~ operator may be my best bet.
Scratch that ... found this message:
http://www.mail-archive.com/[email protected]/msg18598.html
which says I should be able to do a 'SIMILAR TO' construct which is perhaps
somewhat more lightweight than a full regexp.
Thanks,
Michael
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