DECLARE @EvId INT,@PiD INT;
DECLARE Evaluate CURSOR FOR SELECT EvaluateId,ProductId FROM dbo.ProductEvaluate WHERE CreateTime > '2014-10-20 00:00:01';

OPEN Evaluate;
FETCH NEXT FROM Evaluate INTO @EvId,@PiD;
	WHILE @@FETCH_STATUS = 0
	BEGIN
	DECLARE @BDate datetime, @EDate DATETIME,@PDate DATETIME;
	SET @BDate = '20140101' --下限
	SELECT @BDate = CONVERT(varchar(100), CreateTime, 112) FROM dbo.Products WHERE ProductId = @PiD;
	SET @EDate = '20141020 23:59:59' --上限
	UPDATE dbo.ProductEvaluate SET CreateTime =DATEADD(second,ABS(CHECKSUM(NEWID()))%DATEDIFF(second,@BDate,@Edate),@BDate) WHERE EvaluateId = @EvId ;
	FETCH NEXT FROM Evaluate INTO @EvId,@PiD;
	END
CLOSE Evaluate;
DEALLOCATE Evaluate;