在Sproc中多次使用UDF

Question

我正在使用SQL 2k5 sproc。

我需要引用UDF來根據幾個變量和用戶權限計算價格。我最初試圖這一點，但它沒有工作，因爲我沒有引用一個場...

SELECT dbo.f_GetPrice(model,userid,authType) 'YourPrice', name, description 
FROM tblRL_Products 
WHERE 'YourPrice' Between @fromPrice AND @toPrice 
    OR 'YourPrice' IS NULL 

所以我修改這

SELECT dbo.f_GetPrice(model,userid,authType) 'YourPrice', name, description 
FROM tblRL_Products 
WHERE dbo.f_GetPrice(model,userid,authType) Between @fromPrice AND @toPrice 
    OR dbo.f_GetPrice(model,userid,authType) IS NULL 

當SQL執行該存儲過程，它是運行函數3X的每個記錄或它是否運行一次，並使用其他兩個位置每行的值。

有沒有更有效的方法來做到這一點？

---

編輯

這是標量UDF。它需要根據用戶授權的類型獲取價格，然後一旦我們有合適的價格，我們需要對其進行計算。這全部存儲在授權表中。每個用戶都有對每一行產品的授權。因此，他們可能會針對每條線有不同的價格類型和計算方式，在單個搜索結果調用中返回數十行甚至數百行。

在上面的代碼中，我使用了authType，這是一箇舊的調用，我們不再使用該參數。

ALTER function [dbo].[f_GetPrice] 
(
    @model uniqueidentifier, 
    @userID uniqueidentifier  
) 
returns money 
as 
begin 

Declare @yourPrice money 

WITH ProductPrice AS(
SELECT (CASE PriceType 
     WHEN 'msrp' THEN p.price_msrp 
      WHEN 'jobber' THEN p.price_jobber 
      WHEN 'warehouse' THEN p.price_warehouse 
      WHEN 'margin' THEN p.price_margin 
      WHEN 'mycost' THEN p.price_mycost 
      WHEN 'customprice1' THEN p.price_custom1 
      WHEN 'customprice2' THEN p.price_custom2 
      WHEN 'customprice3' THEN p.price_custom2 
      ELSE p.price_msrp 
     END) as YourPrice, aup.calc, aup.amount 
FROM products p 
    JOIN lines l ON l.lineID=l.lineID 
    JOIN authorizations a ON l.authlineID=a.authlineID 
    JOIN authorizationusers au ON a.auID=au.auID 
    JOIN authorizationuserprices aup ON au.aupID=aup.aupID 
WHERE au.userID=@userID AND p.modelID=@model) 


SELECT @yourPrice=(CASE calc 
      WHEN 'amount' THEN YourPrice+amount 
      WHEN 'percent' THEN YourPrice+(YourPrice*amount/100) 
      WHEN 'divide' THEN YourPrice/amount 
      WHEN 'factore' THEN YourPrice*amount 
      WHEN 'none' THEN YourPrice 
      ELSE YourPrice 
      END) FROM ProductPrice 

return @yourPrice 

END 

Answer 1

如果你必須使用這個UDF，那麼使用子查詢和過濾的子查詢外：

select YourPrice, name, description 
from 
(
    SELECT dbo.f_GetPrice(model,userid,authType) YourPrice, name, description 
    FROM tblRL_Products 
) d 
WHERE YourPrice Between @fromPrice AND @toPrice 
    OR YourPrice IS NULL 

然後你只叫你的UDF一次，而不是3倍。

Answer 2

如果標量函數必須應用於相當多的行，則標量函數並不好。在這種情況下，您肯定可以將標量函數轉換爲表值函數，對於每一行輸入數據都不會被調用一次。

create function [dbo].[ft_GetPrice] 
(
    @model uniqueidentifier, 
    @userID uniqueidentifier  
) 
returns table 
as return 
(
    WITH ProductPrice AS (
     SELECT (CASE PriceType 
       WHEN 'msrp' THEN p.price_msrp 
        WHEN 'jobber' THEN p.price_jobber 
        WHEN 'warehouse' THEN p.price_warehouse 
        WHEN 'margin' THEN p.price_margin 
        WHEN 'mycost' THEN p.price_mycost 
        WHEN 'customprice1' THEN p.price_custom1 
        WHEN 'customprice2' THEN p.price_custom2 
        WHEN 'customprice3' THEN p.price_custom2 
        ELSE p.price_msrp 
       END) as YourPrice, aup.calc, aup.amount 
     FROM products p 
      JOIN lines l ON l.lineID=l.lineID 
      JOIN authorizations a ON l.authlineID=a.authlineID 
      JOIN authorizationusers au ON a.auID=au.auID 
      JOIN authorizationuserprices aup ON au.aupID=aup.aupID 
     WHERE au.userID=@userID AND p.modelID=@model 
    ) 
    SELECT 
     CASE calc 
      WHEN 'amount' THEN YourPrice+amount 
      WHEN 'percent' THEN YourPrice+(YourPrice*amount/100) 
      WHEN 'divide' THEN YourPrice/amount 
      WHEN 'factore' THEN YourPrice*amount 
      WHEN 'none' THEN YourPrice 
      ELSE YourPrice 
     END as YourPrice 
    FROM ProductPrice 
) 
GO 

哪些可以再使用：

SELECT fp.YourPrice, name, description 
FROM tblRL_Products 
    outer apply dbo.ft_GetPrice(model, userid, authType) fp 
WHERE fp.YourPrice Between @fromPrice AND @toPrice OR fp.YourPrice IS NULL