UPDATE Sales
SET Sales.price = P.price
FROM Sales
CROSS APPLY (
SELECT TOP (1) price
FROM Price
WHERE Sales.itemId = Price.itemId AND
Sales.date BETWEEN Price.validFrom and Price.ValidTo
ORDER BY Price.validFrom DESC
) AS P
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.