Scalar functions are usually a performance problem because they execute row by row. The best option for performance when you need parameters is an inline table valued function which is written like thisÑ

CREATE FUNCTION hstore_num ()

RETURNS TABLE

AS

RETURN

SELECT TOP 1 'Highest Store Count' = COUNT(state)

FROM stores

GROUP BY state

ORDER BY 'Highest Store Count' DESC;

GO

Of course, with no parameters, you could use a view instead

CREATE VIEW hstore_num

AS

SELECT TOP 1 'Highest Store Count' = COUNT(state)

FROM stores

GROUP BY state

ORDER BY 'Highest Store Count' DESC;

GO

Both of them would be called as a table, but the function needs to use parenthesis.

SELECT *

FROM hstore_num() --

Hope this is clear.