使用基於其他選擇的列之一進行選擇

Question

我正在使用數據庫超文件客戶端/服務器的windev。

我有一個名為Operation的表，帶有colums（accountNumber，日期，金額，operationType）。

operationType可以采用兩個值：“付款”和“取款”。

我想選擇一個帳戶中完成的操作的列表，我的列表應顯示5個列：日期，帳戶編號，金額，操作類型和余額。

最后一欄（余額）應為當前日期之前“付款”類型的所有操作的總和與當前日期之前“提款”類型的所有操作的總和之差

我嘗試以下SQL代碼

SELECT accountNumber, date as dateOpe, amount, operationType, (SUM (SELECT Operation.amount 
                                                                   FROM Operation 
                                                                   WHERE Operation.date<=dateOpe AND Operation.operationType='payment')
                                                             -SUM (SELECT Operation.amount
                                                                   FROM Operation
                                                                   WHERE Operation.date<=dateOpe AND Operation.operationType='withdrawal')) as balance
 FROM Operation

但是我總是有一個錯誤告訴我我無權在SUM中放入選擇

請有人幫我。 請我怎么寫這樣的SQL查詢。

提前致謝

Answer 1

請嘗試以下方法：

SELECT accountNumber, date, amount, operationType, 
       (SELECT SUM(amount) AS balance  
          FROM operation WHERE operationType='payment' and date=date) 
      -(SELECT SUM(amount) AS balance  
          FROM operation WHERE operationType='withdrawal' and date=date) 
       as balance  
       FROM operation

Answer 2

嘗試使用子查詢來查找SUM，如下所示。 可能會有更優雅的解決方案，但這應該可行。

SELECT date, accountNumber,
    operationType, deposits - withdrawals AS balance
FROM Operations o INNER JOIN (
    SELECT accountNumber, SUM(amount) AS withdrawals
    FROM Operaions
    WHERE operationType = 'withdrawal'
    GROUP BY accountNumber
) a ON  o.accountNumber = a.accountNumber
INNER JOIN (
    SELECT accountNumber, SUM(amount) AS deposits
    FROM Operations
    WHERE operationType = 'deposit'
    GROUP BY accountNumber
)b ON o.accountNumber = b.accountNumber

Answer 3

我會使用這樣的事實：如果為false，則邏輯表達式會產生0；如果為true，則邏輯表達式會產生1。 因此，如果表達式為假， Operation.amount * <logical expression>將產生0，如果表達式為真，則將產生Operation.amount 。 因此，以下查詢應接近解決方案（未經測試）：

        SELECT accountNumber, date as dateOpe, amount, operationType, 
               SUM (Operation.amount * (Operation.date<=dateOpe AND Operation.operationType='payment')) -
SUM (Operation.amount * (Operation.date<=dateOpe AND Operation.operationType='withdrawal')) as balance
         FROM Operation