Re: Like problem - Mailing list pgsql-sql

Tom Lane answered this question in a prior post.

Thanks,

Lance Campbell
Project Manager/Software Architect
Web Services at Public Affairs
University of Illinois
217.333.0382
http://webservices.uiuc.edu

-----Original Message-----
From: pgsql-sql-owner@postgresql.org
[mailto:pgsql-sql-owner@postgresql.org] On Behalf Of Campbell, Lance
Sent: Wednesday, February 13, 2008 10:59 AM
To: Richard Huxton
Cc: pgsql-sql@postgresql.org
Subject: Re: [SQL] Like problem

Richard,


The first example you gave me does not work.  Below is the test example
I used (this example should NOT return 'matched'):

SELECT 'matched' WHERE 'abcgxyz' LIKE E'%abc\_x%';
?column?
----------
matched
(1 row)


The second example you gave me does work:

SELECT 'matched' WHERE 'abcgxyz' LIKE '%abcQ_x%' ESCAPE 'Q';
?column?
----------
0 rows returned

SELECT 'matched' WHERE 'abc_xyz' LIKE '%abcQ_x%' ESCAPE 'Q';
?column?
----------
matched
1 row


Why does the first example not work?  I have also tried the following
(the below should not work if they are correct):

SELECT 'matched' WHERE 'abcgxyz' LIKE '%abc' || E'\_' || 'x%';?column?
----------matched
(1 row)

SELECT 'matched' WHERE 'abcgxyz' LIKE '%abc' || E'_' || 'x%';?column?
----------matched
(1 row)

Do you have any thoughts on why none of these examples work with the
'E'?

Thanks,

Lance Campbell
Project Manager/Software Architect
Web Services at Public Affairs
University of Illinois
217.333.0382
http://webservices.uiuc.edu
-----Original Message-----
From: Richard Huxton [mailto:dev@archonet.com]
Sent: Wednesday, February 13, 2008 10:42 AM
To: Campbell, Lance
Cc: pgsql-sql@postgresql.org
Subject: Re: [SQL] Like problem

Campbell, Lance wrote:
> 8.2.5
>
> I am having an issue with trying to use 'LIKE' so that I can match on
a
> string with an underscore in it.  What is the proper way to find the
> following string?

> WARNING:  nonstandard use of escape in a string literal
>
> LINE 1: ...ct c1 from t1 where c1 like '%abc\_%';

Either indicate you are using an escaped string: LIKE E'%abc\_%'
Or, change the escape character: LIKE '%abcQ_%' ESCAPE 'Q'

--   Richard Huxton  Archonet Ltd

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TIP 9: In versions below 8.0, the planner will ignore your desire to      choose an index scan if your joining column's
datatypesdo not      match