Question

I try to create standardized SQL scripts for use in my SSRS reports. If I wish to have a statement such as:

Select * from mytable

and use a SQL Variable (SSRS parameter) in the where clause, is there any speed advantage to using this:

Where field = @MyField

VS.

Where field IN (@MyField)

I know the second option supports both multiple selections and single selections while the first supports only single.

Are there any performance hits if I write all my queries with the IN statement for uniformity?

Answer 1

There is no performance hit. The optimizer converts the IN to a series of = operations ORed together.

As a side note, I hope you’re not really using SELECT * in your actual queries.