Question

I have a stored procedure that uses a view to pull 6 averages. The SQL database is SQL Server 2000. When I run it in the Query analyzer, it takes roughly 9 seconds. What can I do to get better performance? Should I return the rows using LINQ and determine an average that way? Will it be faster?

Here’s an example of my current sproc:

create procedure [TestAvg]
(
    @CustomerNumber int
)
as

select
(select AVG(OrderTime) from OrderDetails where ProductID = 12 and DateDiff(day, DateFulfilled, GetDate()) <= 7 and CustomerNumber = @CustomerNumber) as P12D7,
(select AVG(OrderTime) from OrderDetails where ProductID = 12 and DateDiff(day, DateFulfilled, GetDate()) <= 30 and CustomerNumber = @CustomerNumber) as P12D30,
(select AVG(OrderTime) from OrderDetails where ProductID = 12 and DateDiff(day, DateFulfilled, GetDate()) <= 90 and CustomerNumber = @CustomerNumber) as P12D90,
(select AVG(OrderTime) from OrderDetails where ProductID = 16 and DateDiff(day, DateFulfilled, GetDate()) <= 7 and CustomerNumber = @CustomerNumber) as P16D7,
(select AVG(OrderTime) from OrderDetails where ProductID = 16 and DateDiff(day, DateFulfilled, GetDate()) <= 30 and CustomerNumber = @CustomerNumber) as P16D30,
(select AVG(OrderTime) from OrderDetails where ProductID = 16 and DateDiff(day, DateFulfilled, GetDate()) <= 90 and CustomerNumber = @CustomerNumber) as P16D90

Also, let me clarify the view mentioned above. Since this is SQL Server 2000, I cannot use an indexed view because it does use a subquery. I suppose this can be rewritten to use joins. However, the last time we took a query and rewrote it to use joins, data was missing (because the subquery can return a null value which would omit the entire row).

Answer 1

I would recomend getting the data into a table var first, maybe 2 table vars, 1 for 12 and 1 for 16 ProductID. From these table vars, calculate the avgs as required, and then return tose from the sp.

DECLARE @OrderDetails12 TABLE(
        DateFulfilled DATETIME,
        OrderTime FLOAT
)

INSERT INTO @OrderDetails12
SELECT  DateFulfilled,
        OrderTime
FROM    OrderDetails
WHERE   ProductID = 12
AND     DateDiff(day, DateFulfilled, GetDate()) <= 90
and CustomerNumber = @CustomerNumber

DECLARE @OrderDetails16 TABLE(
        DateFulfilled DATETIME,
        OrderTime FLOAT
)

INSERT INTO @OrderDetails16
SELECT  DateFulfilled,
        OrderTime
FROM    OrderDetails
WHERE   ProductID = 16
AND     DateDiff(day, DateFulfilled, GetDate()) <= 90
and CustomerNumber = @CustomerNumber

Also, creating the correct indexes on the table, will help a lot.