一個（稍微複雜的）SQL查詢？

Question

我有這個複雜（對我）的要求，並希望它的SQL查詢。這裏的交易：

• 有一個名爲「費用」在Access文件中的表。
• 該表格包含「類別」，「金額」，「付款人」和「IsShare」等字段。
• 類別可以是天然氣，雜貨，家庭等...
• 金額是費用的美元金額。
• 付款人可以是我或我的兄弟（「我」或「兄弟」）。
• IsShare可以是真或假。基本上，如果IsShare是真的，那麼費用分爲兩部分。否則，付款人付錢。

我需要一個SQL查詢來計算特定類別的所有費用。應當計算爲這樣：我已經支付的所有非共享項目（付款人=「我」和IsShare =假）的

• 100％，所有共享的項目，I」的
• 50％ （Payer ='我'和IsShare = true），以及
• 我兄弟支付的所有共享項目的50％（Payer ='Bro'AND IsShare = true）。

該查詢應返回所有這三項的總和。

到目前爲止，我有一個初步的查詢，但它返回不正確的結果。有人能幫我糾正嗎？

非常感謝。

return @"SELECT Sum(Amount) AS TotalAmount " + 
     "FROM Expenses " + 
     "WHERE Category = 'Groceries' " + 
     "AND Payer = 'Me' " + 
     "AND Share = false " + 
     "GROUP BY Category " + 
     "UNION " + 
     "SELECT 0.5 * Sum(Amount) AS TotalAmount " + 
     "FROM Expenses " + 
     "WHERE Category = 'Groceries' " + 
     "AND Payer = 'Me' " + 
     "AND Share = true " + 
     "GROUP BY Category " + 
     "UNION " + 
     "SELECT 0.5 * Sum(Amount) AS TotalAmount " + 
     "FROM Expenses " + 
     "WHERE Category = 'Groceries' " + 
     "AND Payer = 'Bro' " + 
     "AND Share = true "; 
     "GROUP BY Category"; 

Answer 1

我不認爲UNION是你需要做的。這將傳遞一次數據並將這些值放在單獨的列中。您可能需要將0.5轉換爲特定類型，但我沒有機會運行這個。

SELECT 
    Category, 
    SUM(CASE WHEN Payer='me' AND NOT IsShare THEN Amount ELSE 0 END) as IPaid, 
    SUM(CASE WHEN Payer='me' AND IsShare THEN Amount * 0.5 ELSE 0 END) as SharedPay, 
    SUM(CASE WHEN Payer='bro' AND IsShare THEN Amount * 0.5 ELSE 0 END) as BrotherPay 
FROM Eexpenses 
WHERE Category = 'Groceries' 
GROUP BY Category 

的MS Access：

SELECT 
    Category, 
    SUM(IIF(Payer='me' AND NOT IsShare, Amount,0)) as IPaid, 
    SUM(IIF(Payer='me' AND IsShare, Amount * 0.5, 0)) as SharedPay, 
    SUM(IIF(Payer='bro' AND IsShare, Amount * 0.5, 0)) as BrotherPay 
FROM Eexpenses 
WHERE Category = 'Groceries' 
GROUP BY Category 

添加了三列在一起：

SELECT Category, IPaid, SharedPay, BrotherPay, IPay + SharedPay + BotherPay as Total 
FROM (
    SELECT 
     Category, 
     SUM(IIF(Payer='me' AND NOT IsShare, Amount,0)) as IPaid, 
     SUM(IIF(Payer='me' AND IsShare, Amount * 0.5, 0)) as SharedPay, 
     SUM(IIF(Payer='bro' AND IsShare, Amount * 0.5, 0)) as BrotherPay 
    FROM Eexpenses 
    WHERE Category = 'Groceries' 
    GROUP BY Category 
) as T1