SQL計特定項目

Question

我需要下表呈現以現在多少漢堡包客戶已納了

客戶|漢堡1數量|漢堡2數量|

我有兩個表：

• 客戶表：與客戶ID，名稱
• 交易秩序：與TransactionOrderID客戶ID和BurgerCode

我有6個漢堡的代碼，爲每一個我需要添加一個列，那麼最好的方法是什麼？

Answer 1

如果你不想使用樞軸，你可以嘗試這樣的事情。

WITH cte AS 
    ( 
    SELECT 
     CustomerID, 
     SUM(CASE WHEN BurgerCode LIKE 'BurgerCode1' THEN 1 ELSE 0 END) AS Burger1Qty, 
     SUM(CASE WHEN BurgerCode LIKE 'BurgerCode2' THEN 1 ELSE 0 END) AS Burger2Qty, 
     SUM(CASE WHEN BurgerCode LIKE 'BurgerCode3' THEN 1 ELSE 0 END) AS Burger3Qty, 
     SUM(CASE WHEN BurgerCode LIKE 'BurgerCode4' THEN 1 ELSE 0 END) AS Burger4Qty, 
     SUM(CASE WHEN BurgerCode LIKE 'BurgerCode5' THEN 1 ELSE 0 END) AS Burger5Qty, 
     SUM(CASE WHEN BurgerCode LIKE 'BurgerCode6' THEN 1 ELSE 0 END) AS Burger6Qty 
    FROM TransactionOrders 
    GROUP BY CustomerID 
    ) 
    SELECT c.*, ct.Name CustomerName FROM cte c JOIN CustomerTable ct ON ct.CustomerID = c.CustomerID