合併含有相同ID但不同的數據轉換成一排兩排

Question

我有一個非常棘手的問題要問你所有

假設我有以下各表

表ACCOUNTTYPE：

Id  Type 
1  Checking 
2  Savings 

表Customer_Account：

Customer_Id  Account_Type_Id 
    450     1 
    450     2 
    451     1 

表Customer_Account包含客戶賬號及其賬戶類型ID列表。 Account_Type_Id是來自AccountType.Id的外鍵。

假設在Customer_Account表，命名爲約什（ID 450）一個客戶可以有既一個檢查和上面示出的儲蓄賬戶作爲。我可以輸出這個客戶與他的ID和像這樣的帳戶類型由具有LEFT JOIN兩次在ACCOUNTTYPE表：

SELECT CustAccount.Customer_Id AS Id, Account1.Type AS Account_Type_1, Account2.Type AS Account_Type_2 
FROM Customer_Account CustAccount 
LEFT JOIN AccountType Account1 
ON Account1.Id = CustAccount.Account_Type_Id 
LEFT JOIN AccountType Account2 
ON Account2.Id = CustAccount.Account_Type_Id 

輸出將是：

Id  Account_Type_1   Account_Type_2   
450   Checking    Checking 
450   Savings    Savings 
451   Checking    Checking 

我是什麼試圖做的是，如果像Josh（id 450）這樣的客戶有這兩個一個檢查和一個儲蓄帳戶，我想輸出上面的兩行數據成一行像這樣：

Id  Account_Type_1  Account_Type_2 
450   Checking   Savings 

還有，如果客戶只有一個類型的帳戶（如客戶ID爲451這裏），我只希望這種類型的賬號對應的列下出現像這樣：

Id  Account_Type_1  Account_Type_2 
451   Checking    

或者，如果客戶ID爲451只有一個儲蓄賬戶的輸出中應該是：

Id  Account_Type_1  Account_Type_2 
451        Savings 

我想「檢查」只Accoun_Type_1和「儲蓄」下出現Account_Type_2下。如果我做一個GROUP BY CustAccount.Customer_Id，我得到這個：

Id  Account_Type_1  Account_Type_2 
450   Checking   Checking 
451   Checking   Checking 

任何專家的任何幫助將是非常讚賞。

謝謝。

Answer 1

這看起來像一個完整的OUTER一個簡單的應用程序連接：

SELECT COALESCE(ac1.id, ac2.id) AS id, ac1.Account_Type_1, ac2.Account_Type_2 
    FROM (SELECT c.Customer_ID AS Id, t.Type AS Account_Type_1 
      FROM Customer_Account AS c 
      JOIN AccountType  AS t ON c.Account_Type_ID = t.ID AND t.ID = 1) AS ac1 
    FULL OUTER JOIN 
     (SELECT c.Customer_ID AS Id, t.Type AS Account_Type_2 
      FROM Customer_Account AS c 
      JOIN AccountType  AS t ON c.Account_Type_ID = t.ID AND t.ID = 2) AS ac2 
    ON ac1.Id = ac2.Id; 

如果你的DBMS不支持FULL OUTER JOIN但支持LEFT OUTER JOIN，那麼你可以使用：

SELECT ac0.id, ac1.Account_Type_1, ac2.Account_Type_2 
    FROM (SELECT DISTINCT c.Customer_ID AS Id FROM Customer_Account AS c) AS ac0 
    LEFT OUTER JOIN 
     (SELECT c.Customer_ID AS Id, t.Type AS Account_Type_1 
      FROM Customer_Account AS c 
      JOIN AccountType  AS t ON c.Account_Type_ID = t.ID AND t.ID = 1) AS ac1 
    ON ac0.id = ac1.id 
    LEFT OUTER JOIN 
     (SELECT c.Customer_ID AS Id, t.Type AS Account_Type_2 
      FROM Customer_Account AS c 
      JOIN AccountType  AS t ON c.Account_Type_ID = t.ID AND t.ID = 2) AS ac2 
    ON ac0.Id = ac2.Id; 

第一個子查詢生成存在的客戶ID列表;第二個生成賬戶類型1（檢查）的列表;第三個生成帳戶類型2（保存）的列表。這些連接可確保每個帳戶都被正確識別。

Answer 2

我覺得this應該幫助你

1：Sql Select Query Question. Merge Rows否則

this應該幫助你

Answer 3

增加更多的條件，您的從句：

ON Account1.Id = CustAccount.Account_Type_Id and Account1.Account_Type_Id = 1 

ON Account2.Id = CustAccount.Account_Type_Id and Account2.Account_Type_Id = 2 

將導致輸出其中包括客戶持有的賬戶。如果他們只有一個帳戶，那麼其他帳戶類型將爲NULL。

編輯：對不起，我不明白，你沒有客戶表。您可以創建一個具有不同Customer_Id值列表的臨時表，並將它用作JOIN中的第一個表。

select distinct Customer_Id into #Customers 
    from Customer_Account 

還是要簡單得多：

select distinct C.Customer_Id, 
    (select 'Checking' from Customer_Account where Customer_Id = C.CustomerId and Account_type_Id = 1) as Account_Type_1, 
    (select 'Savings' from Customer_Account where Customer_Id = C.CustomerId and Account_type_Id = 2) as Account_Type_2, 
    from Customer_Account as C