我應該使用T-SQL函數，查看還是存儲過程？

Question

我有一個關於重用表數據的問題，但是在這種情況下視圖將不起作用，因爲我有一個需要傳入的參數。基本上這部分系統需要將travellerid發送到過程，爲特定旅客返回的安排者名單。有大約7個業務規則用於確定哪些編排器可以返回並且它們是互斥的，所以爲了適應這些可選規則，我在派生查詢中使用了一系列UNION。這是行之有效的，而且在一個相當大的數據庫中性能似乎很好，但是我需要在系統的另外四個部分重用這些規則（UNION）。

我最初試圖用這些UNION創建一個VIEW，但由於每個UNION的邏輯不同和參數的不同需求，所以我在想也許一個函數可以解決這個問題？如果我創建了一個將@travellerid作爲參數並根據業務規則返回arrangerid列表的函數，這是否是理想的/快速的解決方案？我目前在外部查詢中使用UNION ALL和DISTINCT，因爲這比使用UNION來處理數據的唯一性要快得多。

當前程序下面的業務規則（SQL Server 2008中）：

CREATE PROCEDURE [dbo].[getArrangersForTraveller] 
    @travellerid int 
AS 
    DECLARE @costcentreid int 
    DECLARE @departmentid int 

-- Shorthand the traveller costcentre and department for use in queries below 
SET @costcentreid = (SELECT costcentreid FROM traveller WHERE id = @travellerid) 
SET @departmentid = (SELECT departmentid FROM traveller WHERE id = @travellerid) 


SELECT DISTINCT t.id, t.firstname, t.lastname, ti.name AS title, dv.preferred 
FROM traveller t 

INNER JOIN title ti ON t.titleid = ti.id 
    INNER JOIN 

    (

      -- Get Preferred Arrangers linked to Department Groups 
      SELECT dg.arrangerid as id 
      FROM departmentGroup dg 
       INNER JOIN department_departmentGroup ddg 
       ON (dg.id = ddg.departmentGroupId AND ddg.departmentid = @departmentid) 

      UNION ALL 

      -- Get Preferred Arrangers linked to Cost Centre Groups 
      SELECT cg.arrangerid as id 
      FROM costCentreGroup cg 
       INNER JOIN costcentre_costCentreGroup ccg 
       ON (cg.id = ccg.costCentreGroupId AND ccg.costcentreid = @costcentreid) 

      UNION ALL 

      -- If Cost Centre Group has a linked department and this department matches 
      -- the travel arrangers department then return these travel arrangers as well  
      SELECT t3.id 
      FROM costCentreGroup cg1 

       INNER JOIN costcentre_costCentreGroup ccg1 
       ON (cg1.id = ccg1.costCentreGroupId AND ccg1.costcentreid = @costcentreid) 

       INNER JOIN traveller t3 
       ON t3.departmentid = cg1.departmentid  

      WHERE t3.accesslevelid > 1  

      UNION ALL 

      -- Get Direct linked travel arrangers  
      SELECT t1.travelarrangerid as id 
      FROM travelarranger_traveller t1 
      WHERE t1.travellerid = @travellerid 

      UNION ALL 

      -- Get Cost Centre linked arrangers 
      SELECT tc.travelarrangerid as id 
      FROM travelArranger_costcentre tc 
      WHERE tc.costcentreid = @costcentreid 

      UNION ALL 

      -- Get Department linked arrangers 
      SELECT td.travelarrangerid 
      FROM travelArranger_department td 
      WHERE td.departmentid = @departmentid 

      UNION ALL 

      -- Get Company flagged arrangers 
      SELECT t2.id 
      FROM traveller t2 
        INNER JOIN company c ON t2.companyid = c.id 

      WHERE t2.accesslevelid > 1  
      AND ((c.allowTravelArrangerDepartmentAccess = 1 AND t2.departmentid = @departmentid) 
      OR (c.allowTravelArrangerCostCentreAccess = 1 AND t2.costcentreid = @costcentreid)) 

    ) as dv ON dv.id = t.id 

WHERE t.accessLevelid > 1 -- arranger or manager 
AND t.isenabled = 1 
ORDER BY dv.preferred DESC, t.lastname, t.firstname; 

Answer 1

我最初試圖建立與這些工會的視圖，但未由於不同的邏輯在每個工會工作不同的參數要求，所以我想也許一個函數可以解決這個問題？如果我創建了一個作爲param @travellerid的函數，並根據業務規則返回了arrangerid的列表，那麼這是一個理想的/快速的解決方案嗎？

你在考慮程序/ OO編程，但SQL是基於SET的。
一個函數可以工作，但是可以確保當你使用函數作爲判定標準/等時，索引不能被使用。一個非物化視圖只是略好一點;在SQL Server中可以使用索引視圖（也稱爲物化視圖），但它們受到了嚴格限制。它違背了模塊化編程的概念，但是SQL運行得越好，試圖模塊化它的能力就越低，只使用你實際需要的東西。

我重新編寫了您的查詢，但注意到dv.preferred列是在外部查詢中引用的，但不在內部列表中。由於dv是各種表&邏輯的集合體，所以返回的id值在內部查詢之外沒有任何實際值，因爲您需要知道值來自哪個表。這就是說，在這裏它是：

SELECT t.id, t.firstname, t.lastname, ti.name AS title /*, dv.preferred */ 
    FROM TRAVELLER t 
    JOIN title ti ON t.titleid = ti.id 
WHERE (EXISTS(SELECT NULL -- Get Preferred Arrangers linked to Department Groups 
       FROM departmentGroup dg 
       JOIN department_departmentGroup ddg ON ddg.departmentGroupId = dg.id 
                AND ddg.departmentid = @departmentid 
       WHERE dg.arrangerid = t.id) 
    OR EXISTS(SELECT NULL -- Get Preferred Arrangers linked to Cost Centre Groups 
       FROM costCentreGroup cg 
       JOIN costcentre_costCentreGroup ccg ON ccg.costCentreGroupId = cg.id 
                AND ccg.costcentreid = @costcentreid 
       WHERE cg.arrangerid = t.id) 
    OR EXISTS(SELECT NULL -- If Cost Centre Group has a linked department and this department matches the travel arrangers department then return these travel arrangers as well  
       FROM costCentreGroup cg1 
       JOIN costcentre_costCentreGroup ccg1 ON ccg1.costCentreGroupId = cg1.id 
                AND ccg1.costcentreid = @costcentreid 
       JOIN traveller t3 ON t3.departmentid = cg1.departmentid  
           AND t3.accesslevelid > 1 
       WHERE t3.id = t.id) 
    OR EXISTS(SELECT NULL -- Get Direct linked travel arrangers  
       FROM travelarranger_traveller t1 
       WHERE t1.travellerid = @travellerid 
       AND t1.travelarrangerid = t.id) 
    OR EXISTS(SELECT NULL -- Get Cost Centre linked arrangers 
       FROM travelArranger_costcentre tc 
       WHERE tc.costcentreid = @costcentreid 
       AND tc.travelarrangerid = t.id) 
    OR EXISTS(SELECT NULL -- Get Department linked arrangers 
       FROM travelArranger_department td 
       WHERE td.departmentid = @departmentid 
       AND td.travelarrangerid = t.id) 
    OR EXISTS(SELECT NULL -- Get Company flagged arrangers 
       FROM traveller t2 
       JOIN company c ON t2.companyid = c.id 
           AND t2.accesslevelid > 1  
       WHERE ( (c.allowTravelArrangerDepartmentAccess = 1 AND t2.departmentid = @departmentid) 
         OR (c.allowTravelArrangerCostCentreAccess = 1 AND t2.costcentreid = @costcentreid)) 
       AND t2.id = t.id)) 
    AND t.accessLevelid > 1 -- arranger or manager 
    AND t.isenabled = 1 
ORDER BY /*dv.preferred DESC,*/ t.lastname, t.firstname; 

使用子查詢（IN，EXISTS）將緩解自帶的使用是否有連接到母體多個子記錄加入重複的問題。