Hello Suppose that I have the table BusinessWeek(BiWk char(7), InitialDate date, EndDate date). I want to create a function that given a date, it would return the BiWk value corresponding to that value. The following query uses a Table ScanECLARE @BiDay AS DATE SET @BiDay = '2008-05-17'SELECTBiWkFROM BusinessWeekWHERE @BiDay BETWEEN InitialDate AND EndDate How can I boost the performance of this query? What indexes should be created? My intention is to process a large table row by row and to get the Business Week corresponding to a Date Field of that table. Thanks a lot.