避免重复条目使用完全连接和组

Question

我对数据库使用了HSQLDB，在连接两个表时，我必须避免重复条目。

Table1

HMEXPENSE
+--------+---------------+-------------+
| USERID | EXPENSEAMOUNT | EXPENSEDATE |
+--------+---------------+-------------+
|      a |      100      | 2018-10-10  |
|      a |      200      | 2018-10-11  |
|      a |      100      | 2018-10-11  |
|      a |      200      | 2018-10-13  |
+--------+---------------+-------------+

Table2

HMINCOME
+--------+---------------+-------------+
| USERID | EXPENSEAMOUNT | EXPENSEDATE |
+--------+---------------+-------------+
|      a |      200      | 2018-10-10  |
|      a |      100      | 2018-10-11  |
|      a |      200      | 2018-10-11  |
|      a |      100      | 2018-10-12  |
+--------+---------------+-------------+

提供重复条目的当前查询如下所示

SELECT e.expenseDate ,i.incomeDate , SUM(e.expenseAmount), SUM(i.incomeAmount)
FROM HMINCOME i FULL JOIN HMEXPENSE e on i.incomeDate = e.expenseDate 
GROUP BY i.incomeDate,e.expenseDate, i.incomeAmount, e.expenseAmount

输出

+-------------+------------+-------+-------+
| EXPENSEDATE | INCOMEDATE |   C3  |   C4  |
+-------------+------------+-------+-------+
|  2018-10-10 | 2018-10-10 | 100.0 | 200.0 |
|  2018-10-11 | 2018-10-11 | 200.0 | 100.0 |
|  2018-10-11 | 2018-10-11 | 100.0 | 100.0 |
|  2018-10-11 | 2018-10-11 | 200.0 | 200.0 |
|  2018-10-11 | 2018-10-11 | 100.0 | 200.0 |
|   <null>    | 2018-10-12 | <null>| 100.0 |
|  2018-10-13 |   <null>   | 200.0 | <null>|
+-------------+------------+-------+-------+

如果我使用上面提到的查询来获得实际的输出，我的实际场景中需要的输出如下所示

SELECT e.expenseDate, i.incomeDate , SUM(e.expenseAmount),SUM(i.incomeAmount)
FROM HMINCOME i FULL JOIN HMEXPENSE e on i.incomeDate = e.expenseDate 
GROUP BY i.incomeDate,e.expenseDate

输出

+-------------+------------+-------+-------+
| EXPENSEDATE | INCOMEDATE |   C3  |   C4  |
+-------------+------------+-------+-------+
|  2018-10-10 | 2018-10-10 | 100.0 | 200.0 |
|  2018-10-11 | 2018-10-11 | 600.0 | 600.0 |
|   <null>    | 2018-10-12 | <null>| 100.0 |
|  2018-10-13 |   <null>   | 200.0 | <null>|
+-------------+------------+-------+-------+

要求获取单个日的金额和另一个表中不存在的日期的空项。

预期产出如下

+-------------+------------+-------+-------+
| EXPENSEDATE | INCOMEDATE |   C3  |   C4  |
+-------------+------------+-------+-------+
|  2018-10-10 | 2018-10-10 | 100.0 | 200.0 |
|  2018-10-11 | 2018-10-11 | 300.0 | 300.0 |
|   <null>    | 2018-10-12 | <null>| 100.0 |
|  2018-10-13 |   <null>   | 200.0 | <null>|
+-------------+------------+-------+-------+

由于重复的条目，无法正确计算C3和C4列值。

救命..。

Answer 1

解决这一问题的一种方法是使用union all和group by。

select dte, sum(incomeamount) as incomeamount, sum(expenseamount) as expenseamount
from ((select incomedate as dte, incomeamount, 0 as expenseamount
       from hmincome
      ) union all
      (select expensedate, 0, expenseAmount
       from hmexpense
      )
     ) ie
group by dte
order by dte;

Answer 2

这里的问题是，表中的日期有多个行。因此，我们需要首先在子查询中聚合它们。然后，它将被用于执行FULL JOIN。

尝试：

SELECT 
  e.expenseDate,
  i.incomeDate, 
  e.sumExpenseAmount, 
  i.sumIncomeAmount
FROM 
(SELECT incomeDate, SUM(incomeAmount) sumIncomeAmount
 FROM HMINCOME
 GROUP BY incomeDate) i
FULL JOIN 
(SELECT expenseDate, SUM(expenseAmount) sumExpenseAmount
 FROM HMEXPENSE
 GROUP BY expenseDate) e
  ON i.incomeDate = e.expenseDate