一个（稍微复杂的）SQL查询？

Question

我有这个复杂（对我）的要求，并希望它的SQL查询。这里的交易：

• 有一个名为“费用”在Access文件中的表。
• 该表格包含“类别”，“金额”，“付款人”和“IsShare”等字段。
• 类别可以是天然气，杂货，家庭等...
• 金额是费用的美元金额。
• 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，那么费用分为两部分。否则，付款人付钱。

我需要一个SQL查询来计算特定类别的所有费用。应当计算为这样：我已经支付的所有非共享项目（付款人=“我”和IsShare =假）的

• 100％，所有共享的项目，I”的
• 50％ （Payer ='我'和IsShare = true），以及
• 我兄弟支付的所有共享项目的50％（Payer ='Bro'AND IsShare = true）。

该查询应返回所有这三项的总和。

到目前为止，我有一个初步的查询，但它返回不正确的结果。有人能帮我纠正吗？

非常感谢。

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

我不认为UNION是你需要做的。这将传递一次数据并将这些值放在单独的列中。您可能需要将0.5转换为特定类型，但我没有机会运行这个。

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