Thread: BUG #3487: regular exp

The following bug has been logged online:

Bug reference:      3487
Logged by:          Mikhail
Email address:      Tuchkov.Michail@gmail.com
PostgreSQL version: 8.1
Operating system:   windows 2003 SP2
Description:        regular exp
Details:

Please, help me!
My code:
"IF char_length(substring(str from '^[a-zA-Z]*://'))=0 THEN
   str:= 'http://'||str;
END IF;"

If str= http://www.msn.com then nothing happen
(all is OK), but if str= just www.msn.com then nothing happen too!

Why?

Then I experimen with that:
I change '=' to '<>'
 results:
str=http://www.msn.com -> http://http://www.msn.com
str=www.msn.com -> http://www.msn.com

Thank you.

On Thu, Jul 26, 2007 at 05:53:54AM +0000, Mikhail wrote:
>
> The following bug has been logged online:
>
> Bug reference:      3487
> Logged by:          Mikhail
> Email address:      Tuchkov.Michail@gmail.com
> PostgreSQL version: 8.1
> Operating system:   windows 2003 SP2
> Description:        regular exp
> Details:
>
> Please, help me!
> My code:
> "IF char_length(substring(str from '^[a-zA-Z]*://'))=0 THEN
>    str:= 'http://'||str;
> END IF;"
>
> If str= http://www.msn.com then nothing happen
> (all is OK), but if str= just www.msn.com then nothing happen too!
>
> Why?

Because substring() returns NULL when there is no match, not the empty
string. So you need
IF substring(str from '^[a-zA-Z]*://') IS NULL THEN
...

//Magnus