Question

我有一张桌子，记录如下

------------------------------------------------
id |m_id  | primary | secondary  | Duration
------------------------------------------------
1  |  1   | 100     | 80         | 12m
------------------------------------------------
2  |  1   | 50      | 40         | 6m
------------------------------------------------
3  |  2   | 300     | 150        | 12m
------------------------------------------------
4  |  2   | 150     | 70         | 6m
------------------------------------------------
5  |  3   | 500     | 300         | 12m
------------------------------------------------
6  |  3   | 300      | 200         | 6m

我需要这样的输出。请注意，这里是按月显示数据。

--------------------------------------------
id  |m_id | primary        | secondary    
    |     | 12m |6m        |12m   |6m        
--------------------------------------------
1   |1    |100  |50        | 80  |40  
--------------------------------------------
2   |2    |300  |150       | 150  |70 
--------------------------------------------
3   |3    |500  |300       | 300  |200

但是我得到的输出是（我还没有添加金额）

   --------------------------------------------
id  |m_id | primary        | secondary    
    |     | 12m |6m        |12m   |6m        
--------------------------------------------
1   |1    |
--------------------------------------------
1   |1    |
--------------------------------------------
2   |1    |  
--------------------------------------------
3   |2    | 
--------------------------------------------
3   |2    |  
--------------------------------------------
4   |2    |

我尝试查询

SELECT *
FROM `tbl_activityFees2` as `t1`
JOIN `tbl_activityFees2` as `t2` ON `t2`.`m_id`=`t1`.`m_id`
JOIN `activity_name` ON `activity_name`.`m_id`=`t1`.`m_id`
WHERE `t1`.`is_feesActive` = 1
AND `t2`.`is_feesActive` = 1
AND `t1`.`Duration` = '12m'
OR `t2`.`Duration` = '6m'

您能在这个问题上帮助我吗？

Answer 1

您可以按最大逻辑分组，然后按如下所示与主表联接

   select `t1`.id
          ,grouped_data.*
     from(
    SELECT `t1`.m_id
           ,max(case when `t1`.duration='12m' then primary end) as primary_12m
           ,max(case when `t1`.duration='6m' then primary end)  as primary_6m   
           ,max(case when `t1`.duration='12m' then secondary end) as secondary_12m
           ,max(case when `t1`.duration='6m' then secondary end)  as secondary_6m          
      FROM `tbl_activityFees2` as `t1`
     WHERE `t1`.`is_feesActive` = 1
    GROUP BY `t1`.m_id
          ) grouped_data
    JOIN `tbl_activityFees2` as `t1`      
      on t1.m_id=grouped_data.m_id

Answer 2

我将执行完全外部联接。由于MySQL不支持完全外部联接，因此您需要通过UNION设置为OUTER JOIN s来模拟它们，如下所示：

select
  coalesce(t1.m_id, 2.m_id) as m_id,
  t2.primary as primary_12m,
  t1.primary as primary_6m,
  t2.secondary as secondary_12m,
  t1.secondary as secondary_6m
from tbl_activityFees2 t1
left join tbl_activityFees2 t2 
  on t1.m_id = t2.m_id
 and t1.duration = '6m'
 and t2.duration = '12m'
 and t1.is_feesActive = 1
 and t2.is_feesActive = 1
union
select
  coalesce(t1.m_id, 2.m_id) as m_id,
  t2.primary as primary_12m,
  t1.primary as primary_6m,
  t2.secondary as secondary_12m,
  t1.secondary as secondary_6m
from tbl_activityFees2 t2
left join tbl_activityFees2 t1
  on t1.m_id = t2.m_id
 and t1.duration = '6m'
 and t2.duration = '12m'
 and t1.is_feesActive = 1
 and t2.is_feesActive = 1

查询未显示预期的输出

2 个答案: