Question

我有2张桌子的收入和支出。我必须计算费用和收入的总和，并计算两个总和的差异。

我正在使用

SELECT (SUM(a.Amount)-(SELECT SUM(i.Amount) 
FROM incomes i GROUP BY i.UserId)) Expense,
a.UserId FROM amount a GROUP BY a.UserId

目前只有收入表中的UserId，所以当我执行查询时，它会获取UserId收入的总和并减去每个人的开支。

我需要他们的个人差异。

Answer 1

您可以使用subselect

SELECT (q.Amount - q.Expense) AS `diff` FROM
(
(SELECT (SUM(a.Amount) 
FROM amount a GROUP BY a.UserId) AS `Amount`,
(SELECT SUM(i.Amount) 
FROM incomes i GROUP BY i.UserId) AS Expense,
) q

或加入

SELECT (q.Amount - q.Expense) AS `diff` FROM
(
SELECT SUM(a.Amount)  AS `Amount` ,SUM(i.Amount) AS `Expense`
FROM amount 
 JOIN   incomes i ON ( a.UserId=i.UserId)
GROUP BY i.UserId
) q

或者您可以尝试FULL OUTER JOIN，因为它们不存在，但您仍然可以使用UNION

SELECT (q.Amount - q.Expense) AS `diff` FROM
(
(SELECT (SUM(a.Amount) AS `Amount` , NULL AS `Expense`
FROM amount a GROUP BY a.UserId) 
UNION ALL
(SELECT NULL AS `Amount`, SUM(i.Amount) AS Expense
FROM incomes i GROUP BY i.UserId) 
) q

选择一个表中列的总和与另一个表中列的总和之差

1 个答案: