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user defined aggregate function

Posted on 2004-04-05
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Last Modified: 2008-03-17
I need to make my own aggregate function. I'm running sql server 2000, can someone give me an example of how to do this.

btw, this is what I'm trying to do:

given a list of numeric values ie (1,2,2,1,0,2) I need to return 0 if 0 occurs before 1, or 1 if 1 occurs before 0

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Question by:gfody
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mikkelp earned 250 total points
ID: 10761818

You can't write your own aggregate function

check this: http://www.experts-exchange.com/Databases/Microsoft_SQL_Server/Q_20881703.html

I don't believe it's possible to write a function to take a variable number of parameters, but you could probably get around your problem by selecting the "index" of 0 and 1 and compare the two... ie

select case when .... then 1 else 0 end.

where "index" is defined by the sort-order of your query.
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Expert Comment

by:Hilaire
ID: 10763673
Agree with mikkelp

Writing custom aggregate function will be possible with SQL Server 2005 (Yukon)

If you need more support, please post more details on what you want, the queries you already have, and we'll see what can be done

Hilaire
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Author Comment

by:gfody
ID: 10972720
I have a very complicated set of tables for permissions based on the nested sets model. The routine for processing your permission records to determine whether or not you have access to something is a function that reads in all the permission records on your tree and recursively collapses them. I could do it all in sql if I could define an aggregate like the one in my first post.
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