SQL Server：在其他表插入或更新記錄後觸發表的更新列

Question

我有2個表，ShareButton和SharePage。

ShareButton表：

+----+---------------+---------------+ 
| ID | Name   | TotalShare | 
+----+---------------+---------------+ 
| 1 | Facebook  |  0  | 
| 2 | Twitter  |  0  | 
+----+---------------+---------------+ 

SharePage表：

+----+--------------------+-------+---------------+ 
| ID |  URL   | Share | ShareButtonID | 
+----+--------------------+-------+---------------+ 
| 1 | www.abc.xyz/page1 | 3 |  1  | 
| 2 | www.abc.xyz/page1 | 14 |  2  | 
| 3 | www.abc.xyz/page2 | 6 |  1  | 
| 4 | www.abc.xyz/page2 | 10 |  2  | 
+----+--------------------+-------+---------------+ 

插入後或更新SharePage表中的記錄中，ShareButtonTotalShare列被更新

update ShareButton 
set TotalShare = (sum(Share) from SharePage where "ShareButtonID" = ShareButtonID of updated/inserted record)) 
where ID = ShareButtonID of updated/inserted record)` 

感謝 讀！

Answer 1

讓我先說我同意穆雷尼克的回答。除非你有一個非常糟糕的表現，使用一個簡單的查詢組獲得總和，我不建議將這個總和保存在ShareButton表中。

如果你真的想要一個觸發器來計算的話，我想做到這一點最簡單的方法是這樣的：

CREATE TRIGGER trSharePage_Changed ON SharePage 
FOR UPDATE, INSERT, DELETE 
AS 

UPDATE buttons 
SET TotalShare = SumOfShares 
FROM ShareButton buttons 
INNER JOIN 
(
    SELECT ShareButtonID, SUM(Share) As SumOfShares 
    FROM SharePage 
    GROUP BY ShareButtonID 
) pages ON buttons.ID = pages.ShareButtonID 

注意，該觸發器將之後的任何插入，更新被解僱或表SharePage delete語句將完成。由於它是一個後觸發器，你根本不需要處理插入和刪除的表。