You generate a daily report according to the following query:
You need to improve the performance of the query.
What should you do?
A. Drop the UDF and rewrite the report query as follows:
WITH cte(CustomerID, LastOrderDate) AS (
SELECT CustomerID, MAX(OrderDate) AS [LastOrderDate]
FROM Sales.SalesOrder
GROUP BY CustomerID
)
SELECT c.CustomerName
FROM cte
INNER JOIN Sales.Customer c ON cte.CustomerID = c.CustomerID
WHERE cte.LastOrderDate < DATEADD(DAY, -90, GETDATE())
B. Drop the UDF and rewrite the report query as follows:
SELECT c.CustomerName
FROM Sales.Customer c
WHERE NOT EXISTS (
SELECT s.OrderDate
FROM Sales.SalesOrder s
WHERE s.OrderDate > DATEADD(DAY, -90, GETDATE())
AND s.CustomerID = c.CustomerID)
C. Drop the UDF and rewrite the report query as follows:
SELECT DISTINCT c.CustomerName
FROM Sales.Customer c
INNER JOIN Sales.SalesOrder s ON c.CustomerID = s.CustomerID
WHERE s.OrderDate < DATEADD(DAY, -90, GETDATE())
D. Rewrite the report query as follows:
SELECT c.CustomerName
FROM Sales.Customer c
WHERE NOT EXISTS (SELECT OrderDate FROM Sales.ufnGetRecentOrders(c.CustomerID, 90))
Rewrite the UDF as follows:
CREATE FUNCTION Sales.ufnGetRecentOrders(@CustomerID int, @MaxAge datetime)
RETURNS TABLE AS RETURN (
SELECT OrderDate
FROM Sales.SalesOrder s
WHERE s.CustomerID = @CustomerID
AND s.OrderDate > DATEADD(DAY, -@MaxAge, GETDATE())
