mysql - 如何将 2 个查询结果连接在一起？

Question

场景: 我有 2 个查询表单 1 个表，只想将两个查询结果作为单个查询结果查看。

详细信息: 表:loantrans

+-----+----------+---------+---------+---------+
| tid |   date   | account | purpose |    out  |
+-----+----------+---------+---------+---------+
|  1  |2014-08-12|   975   |  Loan   |   5000  |
|  2  |2014-08-12|   975   |Interest |   850   |
|  3  |2014-08-12|   975   |  Loan   |   150   |
|  4  |2014-08-12|   975   |Interest |   5000  |
+-----+----------+---------+---------+---------+

查询 1:

SELECT MONTH(`loantrans`.`date`) as month, SUM(`loantrans`.`out`) AS loanout
            FROM loantrans
            WHERE  (`loantrans`.`date` BETWEEN '2014-01-01' AND '2014-09-20')
            AND (`loantrans`.`purpose` = 'Loan')
            GROUP BY MONTH(`loantrans`.`date`)
            ORDER BY `loantrans`.`date`

结果:

+-------+---------+
| month | loanout |
+-------+---------+
|   1   |  28000  |
|   2   |  27000  |
|   3   |  10200  |
|   4   |  7000   |
|   5   |  95000  |
|   6   |  2000   |
+-------+---------+

查询 2:

SELECT MONTH(`loantrans`.`date`) as month, SUM(`loantrans`.`out`) AS intout
            FROM loantrans
            WHERE  (`loantrans`.`date` BETWEEN '2014-01-01' AND '2014-09-20')
            AND (`loantrans`.`purpose` = 'Interest')
            GROUP BY MONTH(`loantrans`.`date`)
            ORDER BY `loantrans`.`date`

结果:

+-------+---------+
| month |  intout |
+-------+---------+
|   1   |  2000   |
|   2   |  750    |
|   3   |  200    |
|   4   |  180    |
|   5   |  570    |
|   6   |  625    |
+-------+---------+

我想要的是这样的

+-------+---------+---------+
| month |  intout | loanout |
+-------+---------+---------+
|   1   |  2000   |  28000  |
|   2   |  750    |  27000  |
|   3   |  200    |  10200  |
|   4   |  180    |  7000   |
|   5   |  570    |  95000  |
|   6   |  625    |  2000   |
+-------+---------+---------+

如何得到这样的结果？？？

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Answer 1

  SELECT MONTH(lt.date) month, 
         SUM((lt.purpose='Interest')*lt.out) intout,
         SUM((lt.purpose='Loan')*lt.out) loanout
    FROM loantrans lt
   WHERE lt.date BETWEEN '2014-01-01' AND '2014-09-20'
  /* AND lt.purpose IN ('Interest', 'Loan') /* If you have more purposes. */  
GROUP BY month
ORDER BY month