Thanks for ur response. I used the approach as below and it worked much 
faster and reduced the execution time by 5 times. I concatenated the 3 
fields i wanted to compare and used it as the id. But the query still takes 
like 3 minutes. Earlier it used to take 12 minutes.  Can I optimise it any 
further. Please help. My query is as follows:

SELECT distinct a.playlist,a.material_id,a.destination_locator, 
a.device_name,a.source_locator,a.source from record1 a left outer join 
record2 b on 
where b.material_id+b.destination_locator+b.device_name is null

help is greatly appreciated.


>From: Dan Koken <[EMAIL PROTECTED]>
>Subject: [PHP-DB] Re: subtracting one query from the other
>Date: Thu, 27 Jun 2002 05:24:41 -0700
>Not sure what your data looks like or what exactly you are trying to do.
>But what is wrong with the old standard compare for NULL. Something like
>  as first_id,
> as second_id
>FROM  second_record
>LEFT JOIN first_record
>ON =
>ORDER BY something
>HAVING first_id = NULL
>Here only the second_records will be selected if there is no matching
>HTH.. Good luck .. Dan
>Harpreet Kaur wrote:
>>Please help, I am stuck and my mind is frozen.
>>I want to subtrack one query from the other. I have one query that
>>brings all the records. The second gets another set of records.
>>I want to subtract the second query from the first one . How do i do this?
>>First query produces like 1000 records. Second has like 800 records i
>>want to display the other 200 that dont exist in the first query.
>>Please help.
>>I have this but it is too slow and doesnt work in php but does in mssql.
>>select distinct a.playlist,
>>         a.material_id,
>>         a.destination_locator,
>>         a.destination,
>>         a.air_time,
>>         a.traffic_duration,
>>         a.comment,
>>         a.title,
>>         a.device_name,
>>         m.media_locator as source_locator,
>>         m.medium_name as source
>>from cch_dubber_dublist_view11 a left outer join lib_copy_view m
>>on a.material_id=m.material_id where (A.material_id is not null) and
>>(A.material_id <>'')
>>        select null
>>        from
>>           dev_device_view d
>>        inner join
>>             lib_copy_view c
>>        on
>>             d.device_name= c.medium_name
>>        where
>>            c.material_id = a.material_id
>>            AND c.media_locator = a.destination_locator
>>            AND d.device_name = a.device_name
>>    )
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