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]>
>To: [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
>first_record.id as first_id,
>second_record.id as second_id
>LEFT JOIN first_record
>ON first_record.id = second_record.id
>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.
>>I have this but it is too slow and doesnt work in php but does in mssql.
>>select distinct a.playlist,
>> 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
>> NOT EXISTS (
>> select null
>> dev_device_view d
>> inner join
>> lib_copy_view c
>> d.device_name= c.medium_name
>> c.material_id = a.material_id
>> AND c.media_locator = a.destination_locator
>> AND d.device_name = a.device_name
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