>The calls to UDFs are very expensive. If UDF is called for each record than it'll slow down query significantly. The first one guaranties that UDF will be called only 2 times. The second case depends on how smart SQL Query optimizer is.

That's what I expected, but was hoping for confirmation. If the UDF performs a query, it may be better to do the UDF's query as a derived table?

>
>>I've inherited a system with SQL stored procedures and functions. I want to clarify my understanding.
>>
>>Would this ...
>>
>>select @startdate = dbo.myfunction(@startdate)
>>select @enddate = dbo.myfunction(@enddate)
>>
>>SELECT * from table where datefield between @startdate and @enddate
>>
>>be better than this...
>>
>>SELECT * from table where datefield between dbo.myfunction(@startdate) and dbo.myfunction(@enddate)