Re: Escape wildcard problems.

Alan Hodgson wrote:
> On Friday 24 October 2008, "Gauthier, Dave" <dave.gauthier@intel.com> wrote:
>> I read in the docs (section 9.7.1) that the backslash... \ ... is the
>> default escape char to use in "like" expressions.  Yet when I try it, it
>> doesn't seem to work the ay I expect.  Here's an example...
>>
>> select name from templates where name like '%\_cont\_%';
>>
>
> Use double \\ for underscores. I don't know why it's necessary, but it works
> here.

Here's why. See the documentation for more information:


craig=> show standard_conforming_strings;
 standard_conforming_strings
-----------------------------
 off
(1 row)

craig=> SELECT '%\_cont\_%';
WARNING:  nonstandard use of escape in a string literal
LINE 1: SELECT '%\_cont\_%';
               ^
HINT:  Use the escape string syntax for escapes, e.g., E'\r\n'.
 ?column?
----------
 %_cont_%
(1 row)

craig=> SELECT E'%\\_cont\\_%';
  ?column?
------------
 %\_cont\_%
(1 row)

craig=> set standard_conforming_strings = 1;
SET

craig=> SELECT '%\_cont\_%';
  ?column?
------------
 %\_cont\_%
(1 row)



--
Craig Ringer