如何創建一個用戶定義函數的SQL服務器

Question

這是一個相當溫和的問題，但是

我有我試圖簡化可讀性相當大的存儲過程

它包含了許多union子句與像下面圖1所示

圖1的一個聲明

SELECT COUNT(1) AS Total 
    FROM Orders 
    WHERE (NOT EXISTS (
     SELECT 1 
     FROM (
      SELECT Id 
      FROM OrderLineItems 
      WHERE Orders.Id = Order_Id) AS Sub 
     WHERE EXISTS (
      SELECT 1 
       FROM NormalizedLineItems 
       WHERE (Sub.Id = OrderLineItem_Id) 
       AND (OutOfStock = 1)))) 
    AND (EXISTS (
     SELECT 1 AS Total 
     FROM OrderShipments 
     WHERE (Orders.Id = Order_Id) 
      AND (CarrierApproved = 0))) 
    AND (IsQuote = 0) 
    AND (Cancelled = 0) 
    AND (Archived = 0) 
    AND (Completed = 0) 
    AND (Holding = 0) 

但是也有很多REOC curring圖案在每個語句

以下圖案變成了幾次圖2

圖2

WHERE (NOT EXISTS (
     SELECT 1 
     FROM (
      SELECT Id 
      FROM OrderLineItems 
      WHERE Orders.Id = Order_Id) AS Sub 
     WHERE EXISTS (
      SELECT 1 
       FROM NormalizedLineItems 
       WHERE (Sub.Id = OrderLineItem_Id) 
       AND (OutOfStock = 1)))) 

進出口試圖（出於可讀性目的）減少在存儲在主代碼程序

所以我認爲ID性能測試的UDF，我想出了以下圖3

圖3

SET ANSI_NULLS ON 
GO 

SET QUOTED_IDENTIFIER ON 
GO 

CREATE FUNCTION TestFunction (@OrderId int) 
RETURNS TABLE 
AS 
    RETURN 
    (
    -- Add the SELECT statement with parameter references here 
    SELECT 1 AS Total 
    FROM (
     SELECT OrderLineItems.Id AS Id 
     FROM OrderLineItems 
     WHERE @OrderId = Order_Id) AS Sub 
    WHERE EXISTS (
     SELECT 1 AS Total 
      FROM NormalizedLineItems 
      WHERE (Sub.Id = OrderLineItem_Id) 
      AND (OutOfStock = 1))) 
GO 

所有雖然上述編譯，我真的不知道我在正確的軌道上，我遇到各種各樣的問題試圖上述UDF向原查詢

我在想，如果有人可以給我從圖1如何抽象圖2的具體例子爲UDF這樣我就可以至少性能測試解決方案，看看它的價值，而

注：我知道用戶定義的功能可能是一場性能噩夢，但即使我不能在一個階段，我也不會

SELECT COUNT(1) AS Total 
    FROM Orders 
    join order_ids 
    on order_ids.order_id = Orders.order_id 
... 

如果再次發生語句只在一個：EST

感謝

Answer 1

只名爲ORDER_ID

Insert into order_ids 
select order_id from 
    FROM Orders 
    WHERE (NOT EXISTS (
     SELECT 1 
     FROM (
      SELECT Id 
      FROM OrderLineItems 
      WHERE Orders.Id = Order_Id) AS Sub 
     WHERE EXISTS (
      SELECT 1 
       FROM NormalizedLineItems 
       WHERE (Sub.Id = OrderLineItem_Id) 
       AND (OutOfStock = 1)))) 

然後你就可以簡化您的SQL像這樣的列上創建order_ids表查詢， Common Table Expression是最佳選擇：

with CTE_order_ids as 
(select order_id from 
    FROM Orders 
    WHERE (NOT EXISTS (
     SELECT 1 
     FROM (
      SELECT Id 
      FROM OrderLineItems 
      WHERE Orders.Id = Order_Id) AS Sub 
     WHERE EXISTS (
      SELECT 1 
       FROM NormalizedLineItems 
       WHERE (Sub.Id = OrderLineItem_Id) 
       AND (OutOfStock = 1)))) 
) 
SELECT COUNT(1) AS Total 
    FROM Orders 
    join CTE_order_ids 
    on order_ids.order_id = Orders.order_id 
...