Re: Q: To check a record's existence in a table, FAST!

In <3365fc27.2523204_at_news.netvigator.com> budlo_at_netvigator.com (Bud Lo) writes:
>On Tue, 29 Apr 1997 07:28:24 -0500, Marc <marcm_at_computek.net> wrote:
 

>>Bud Lo wrote:
>>>
>>> To check a record's existence in a table. ( i am using Oracle 7)
>>
>>I have read your proposed solution and other's response. they are all
>>feasible. However, I have one question for you:
>>
>>Why do you want to check a records existance?
>>
>>Many times the reason is to know whether to insert or to update. If
>>this is the case then the most efficient method is to attempt the
>>update and check to see if there is NO_DATA_FOUND. If there is
>>NO_DATA_FOUND then do the insert. You will have saved one fetch
>>over doing a check, then either an insert or update.
>>I'm not sure what your purpose for the check is but many many times
>>the above reason is the case.
 

>In my case, it's not check for update or insert, my main use is for
>resource deallocation and validation. e.g. I need to check whether an
>allocated resource is still being used by some entities. If no entity
>is using it (i.e., count(rowid)=0) then i can deallocate the resource.
 

>Our system is designed for use in Telephone Exchange network, you
>might have heard the telephone switch system like NEAX, FETEX and
>terminology like TGN,TGX, NOC, ROUTE, etc...

You could also use triggers to increment/decrement a counter...

Best regards

        Martin

-- 
               Martin Schr"oder, MS_at_Dream.HB.North.DE
Also an Frauen nasche ich zu gerne rum (die sind auch viel kalorien-
        "armer als der Unsinn aus der Konditorei). (Noses)