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Editorial Team
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Asked: 2026-05-13T23:26:16+00:00

I am maintaining a function in SQL Server 2005, that based on an integer

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I am maintaining a function in SQL Server 2005, that based on an integer input parameter needs to call different functions e.g.

IF @rule_id = 1
   -- execute function 1
ELSE IF @rule_id = 2
   -- execute function 2
ELSE IF @rule_id = 3
   ... etc

The problem is that there are a fair few rules (about 100), and although the above is fairly readable, its performance isn’t great. At the moment it’s implemented as a series of IF’s that do a binary-chop, which is much faster, but becomes fairly unpleasant to read and maintain. Any alternative ideas for something that performs well and is fairly maintainable?

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1 Answer

  1. Editorial Team

    I would suggest you generate the code programatically, eg. via XML+XSLT. the resulted T-SQL will be the same as you have now, but maintaining it would be much easier (adding/removing functions).

    Inside a function you don’t have much choice, using IFs is pretty much the only solution. You can’t do dynamic SQL in functions (you can’t invoke exec). If its a stored procedure, then you have much more libery as you can use dynamic SQL and have tricks like a lookup table: select @function = function from table where rule_id = @rule_id; exec sp_executesql @function;.

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