You can use a powerful but little-known technique, namely a running update with variables:

DECLARE @Sales DECIMAL(10,2), @MV DECIMAL(10,2)

SELECT @Sales = 0, @MV = 0

UPDATE Table1

SET @MV = MV = CASE WHEN nDay = 1 THEN Sales ELSE 0.8*@MV + 0.2*Sales END,

@Sales = Sales

You do need a clustered index on the field that determines the order (nDay in this case) to ensure that the rows are updated in the right order. This method is MUCH faster than using a cursor or a while loop!

Jorg Jansen

Manager Database Development

Infostradasports.com

Nieuwegein

The Netherlands