Thread: Regular Expression Match Operator escape character

Hi,

We're running PostgreSQL v8.2.3 on RHEL5.

In some places in our application, we use Regular Expression Match Operator
(~* => Matches regular expression, case insensitive) inside WHERE criteria.

Example:
SELECT ... 
FROM ...
WHERE (SKILLS ~*
'(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)C#(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)' OR SKILLS ~*
'(^|\\^|\\||[^0-9|^a-z|^A-Z]|$).NET(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)')

In this case, we're trying to search/match for either "C#" OR ".NET" in
SKILLS column.

My question here is, do I need to escape the characters "#" and "."  here?

Regards,
Gnanam

On 2010-12-08, Gnanakumar <gnanam@zoniac.com> wrote:
> Hi,
>
> We're running PostgreSQL v8.2.3 on RHEL5.
>
> In some places in our application, we use Regular Expression Match Operator
> (~* => Matches regular expression, case insensitive) inside WHERE criteria.
>
> Example:
> SELECT ... 
> FROM ...
> WHERE (SKILLS ~*
> '(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)C#(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)' 
>     OR SKILLS ~*
> '(^|\\^|\\||[^0-9|^a-z|^A-Z]|$).NET(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)')
>
> In this case, we're trying to search/match for either "C#" OR ".NET" in
> SKILLS column.
>
> My question here is, do I need to escape the characters "#" and "."  here?

yes. ( '.' especially, I don't think '#' has a special meaning in regex)
but as postgres uses posix extended regex simply escaping every non-letter
character is safe.

(^|\\^|\\||[^0-9|^a-z|^A-Z]|$)

seems to be another way to write
(^|$|[^0-9a-zA-Z])
both of which are locale dependant but that may not be an issue for you.


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