Re: BUG #3487: regular exp

[Magnus Hagander <magnus(at)hagander(dot)net>]

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(dot)Michail(at)gmail(dot)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