Question

我想基于episodes.id_e和episodes.id_mp_e对数据进行分组。

运行此代码时

SELECT * 
    FROM  link_relation, 
          episodes, 
          master_post 
   WHERE link_relation.id_mp_lr = master_post.id_mp 
     AND episodes.id_mp_e = master_post.id_mp 
     AND episodes.no_e = link_relation.no_e_lr 
    GROUP BY episodes.id_e 
    ORDER BY episodes.tanggal_e DESC`


The result what I am getting is :

id_mp_e       no_e         column_n
============  ===========  ===============
1             EP02         xxxxxxxxx
2             EP01         xxxxxxxxx
2             EP01         xxxxxxxxx
1             EP01         xxxxxxxxx
1             EP01         xxxxxxxxx

我要对id_mp_e和no_e进行分组才能获得这样的结果

id_mp_e       no_e         column_n
============  ===========  ===============
1             EP02         xxxxxxxxx
2             EP01         xxxxxxxxx
1             EP01         xxxxxxxxx

上方的表仅显示id_mp_e和no_e的值。

Answer 1

您似乎在错误的列上分组了。您在哪里：

GROUP BY episodes.id_e

您应该指定要分组的列：

GROUP BY episodes.id_mp_e, episodes.no_e

Answer 2

只需使用逗号分隔，在episodes.id_mp_e子句中再添加一个字段（GROUP BY）

SELECT * FROM  link_relation, episodes, master_post 
WHERE link_relation.id_mp_lr = master_post.id_mp 
AND episodes.id_mp_e = master_post.id_mp 
AND episodes.no_e = link_relation.no_e_lr 
GROUP BY episodes.id_mp_e, episodes_no_e
ORDER BY episodes.tanggal_e DESC

如何对数据库中的数据进行分组

2 个答案: