Question

我有两个表 payroll_advance 和 payroll_advrtn ，我应该做完全外部联接以获取我的需求结果。但是，我确定完全外部联接isn'可能在mysql中我也知道通过使用union可以完全外连接。但我不知道如何在以下查询中加入。

我的 payroll_advance 表产生以下结果。

SELECT _id,_tid,_dt,sum(_amount) as _advance FROM payroll_advance WHERE YEAR( _dt )=YEAR(CURDATE()) AND MONTH(_dt) = MONTH(CURDATE()) group by _tid;

+-----+-------+------------+---------+
| _id | _tid  | _dt        | _advance|
+-----+-------+------------+---------+
|  17 | hjg   | 2012-04-18 |    2151 |
|  22 | RKT01 | 2012-04-10 |    2098 |
|  14 | RKT04 | 2012-04-18 |    1511 |
|  16 | RKT09 | 2012-04-09 |     250 |
|  15 | RKT10 | 2012-04-17 |    1313 |
|   8 | RKT21 | 2012-04-03 |    1321 |
|  19 | RKT31 | 2012-04-26 |    2512 |
|  20 | RKT33 | 2012-04-10 |    2250 |
|  25 | T01   | 2012-04-11 |    2500 |
+-----+-------+------------+---------+

payroll_advrtn给出了以下结果。

SELECT _id,_tid,_dt,sum(_amount) as _advrtn FROM payroll_advrtn WHERE YEAR( _dt ) = YEAR(CURDATE()) AND MONTH(_dt) = MONTH(CURDATE()) group by _tid;
+-----+-------+------------+---------+
| _id | _tid  | _dt        | _advrtn |
+-----+-------+------------+---------+
|   9 | RKT02 | 2012-04-10 |    2500 |
|   8 | RKT04 | 2012-04-20 |     150 |
+-----+-------+------------+---------+

但是我想通过结合以上两个结果来得到类似以下结果的东西。

 +------+-------+-------+------------+----------+---------+
| _id  | _tid  | _tid  | _dt        | _advance | _advrtn |
+------+-------+-------+------------+----------+---------+
|   17 | hjg   | NULL  | 2012-04-18 |     2151 |    NULL |
|   22 | RKT01 | NULL  | 2012-04-10 |      999 |    NULL |
|   14 | RKT04 | RKT04 | 2012-04-18 |       11 |     150 |
|   16 | RKT09 | NULL  | 2012-04-09 |      250 |    NULL |
|   15 | RKT10 | NULL  | 2012-04-17 |     1313 |    NULL |
|    8 | RKT21 | NULL  | 2012-04-03 |     1321 |    NULL |
|   19 | RKT31 | NULL  | 2012-04-26 |     2512 |    NULL |
|   20 | RKT33 | NULL  | 2012-04-10 |     2250 |    NULL |
|   25 | T01   | NULL  | 2012-04-11 |     2500 |    NULL |
| NULL | NULL  | RKT02 | NULL       |     NULL |    2500 |
+------+-------+-------+------------+----------+---------+

任何帮助将不胜感激。谢谢!!

Answer 1

为了FULL OUTER JOIN you can do LEFT OUTER JOIN和UNION与RIGHT OUTER JOIN（~~，前提是MySql仍然没有支持FULL OUTER JOIN~~ ）：

select * from A as a
    left outer join B as b on a.col = b.col
union
select * from A as a
    right outer join B as b on a.col = b.col

请注意，您可以使用A和B的子查询 - 这应该适用于您的查询。在你的情况下：

select * from (SELECT * FROM t1) as a
    left outer join (SELECT * FROM t2) as b on a._tid = b._tid
union
select * from (SELECT * FROM t1) as a
    right outer join (SELECT * FROM t2) as b on a._tid = b._tid

结果等于（假设我在复制粘贴数据时没有错误）：

+------+-------+------------+----------+------+-------+------------+----------+
| _id  | _tid  | _dt        | _advance | _id  | _tid  | _dt        | _advartn |
+------+-------+------------+----------+------+-------+------------+----------+
|   17 | hjg   | 2012-04-18 |     2151 | NULL | NULL  | NULL       |     NULL |
|   22 | RKT01 | 2012-04-10 |     2098 | NULL | NULL  | NULL       |     NULL |
|   14 | RKT04 | 2012-04-18 |     1511 |    8 | RKT04 | 2012-04-20 |      150 |
|   16 | RKT09 | 2012-04-09 |      250 | NULL | NULL  | NULL       |     NULL |
|   15 | RKT10 | 2012-04-17 |     1313 | NULL | NULL  | NULL       |     NULL |
|    8 | RKT21 | 2012-04-03 |     1321 | NULL | NULL  | NULL       |     NULL |
|   19 | RKT31 | 2012-04-26 |     2512 | NULL | NULL  | NULL       |     NULL |
|   20 | RKT33 | 2012-04-10 |     2250 | NULL | NULL  | NULL       |     NULL |
|   25 | T01   | 2012-04-11 |     2500 | NULL | NULL  | NULL       |     NULL |
| NULL | NULL  | NULL       |     NULL |    9 | RKT02 | 2012-04-10 |     2500 |
+------+-------+------------+----------+------+-------+------------+----------+

Answer 2

存储两个查询的结果，如下所示：

create temporary table a as select ... ;
create temporary table b as select ... ;

然后：

select * from a left join b using (_tid)
union
select * from a right join b using (_tid);

如何做完全外连接来组合mysql中的两个表？

2 个答案: