是否有可能建立在SQL Server中查找類型的功能或者是這些劣質總是(性能),只是寫的子查詢/加入?SQL服務器查找函數
我想採取一些這樣的代碼
SELECT
ContactId,
ProductType,
SUM(OrderAmount) TotalOrders
FROM
(
SELECT
ContactId,
ProductType,
OrderAmount
FROM
UserOrders ord
JOIN
(
SELECT
ProductCode,
CASE
--Complex business logic
END ProductType
FROM
ItemTable
) item
ON
item.ProductCode=ord.ProductCode
) a
GROUP BY
ContactId,
ProductType
,而是能夠寫一個這樣的查詢
SELECT
ContactId,
UDF_GET_PRODUCT(ProductCode) ProductType,
SUM(OrderAmount) TotalOrders
FROM
UserOrders
GROUP BY
ContactId,
UDF_GET_PRODUCT(ProductCode)