Re: Odd behavior with LIKE?

On Mon, Jun 11, 2001 at 11:00:36AM -0700, some SMTP stream spewed forth:
> I've noticed that if I don't preceed an underscore character ( _ )
> with a double backslash ( \\ ), then a select using LIKE
> ignores the underscore. For example, I have a couple of indexes
> that end with "_ts" and a few tables that end in "ts":

Quote /usrs-lounge/docs/7.1/user/functions-matching.html#FUNCTIONS-LIKE
...
An underscore (_) in pattern stands for (matches) any single character; a
percent sign (%) matches any string of zero or more characters.
...
'abc' LIKE '_b_' true

> select relname from pg_class where relname not like 'pg\\_%' and relname not like '%\\_pkey' and relname not like '\\_ts';
>
> Question is: Why must the underscore character
> be prefixed with a double-backslash?

It must be escaped because it a special pattern-matching character.

gh

> Tim
>