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For one report I am making query where users suppose have to choice TOP values based on percents or fix amount of rows.

I have two ideas

Calling two different sub sproc based on passed param.

if @param ='percent'
begin
      exec sp_data_TOP_by_Percent
end
if @param ='perRow'
begin
    exec sp_data_TOP_by_PerRow
end

other idea is to make dynamic TSQL query something like this

declare @command nchar(max)

select @command = 'select top(10) '
                   + case @param 
                              when 'percent' then percent 
                              else ' '
                     end
                   + ' * '
                   + 'from table 
                        order by 1';
exec sp_executesql @command

Is there third solution for something like this ?
What is better approach ? First one avoiding dynamic TSQL but is harder to maintain code in two places. I am using MSSQL2005 as databse.

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I'd certainly go with @gbn's route of two procedures. A "helper" procedure wrapping other calls feels wrong but its a perfectly acceptable approach. –  Mark Storey-Smith Oct 27 '11 at 21:35

2 Answers 2

up vote 4 down vote accepted

I'd have 2 separate queries/stored procedures just to avoid dynamic SQL.

An IF statement in one stored proc would be enough too

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To elaborate on gbn's answer, two sprocs is the better way to go here; additionally, I'd go one step further and place the query (sans top clause) in a table-valued function and then have the sprocs be nothing more than a shell which calls the TVF and applies the top clause appropriately (by number of rows or percent).

The only caveat here being that if you use a TVF, try and make sure that it's an inlined TVF, as it allows the query analyzer to use statistics (much like it would a view).

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Thanks for this answer and welcome to dba.se Casper –  Jack Douglas Oct 28 '11 at 22:50

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