🚀 go-pugleaf

The UNION should be faster because the OR clause in the first statement will 
prevent the use of an index on prefix.

Dan

"Jason Summers" <jason@grinc.org> wrote in message 
news:472bd113$1@newsgroups.borland.com...
> Hello Again,
>
> I'm curious as to the speed of the UNION statement.  I have a CONTACTS 
> table, which contains phone number prefix fields: HPHONEPREFIX, 
> MPHONEPREFIX, (and others, but we'll omit those for brevity).  These 
> fields are indexed.
>
> Comparing these two statements:  Say I want all people who have any phone 
> number with '573' prefix.
>
> select CONTACTID from CONTACTS where (HPHONEPREFIX = '573') OR 
> (MPHONEPREFIX = '573')
>
> As compared to this:
> select CONTACTID from CONTACTS where HPHONEPREFIX = '573'
> UNION
> select CONTACTID from CONTACTS where MPHONEPREFIX = '573'
>
> Will there be extra overhead using UNION?
>
> Thanks,
> - Jason