Question

我想订购＆＃34;联系＆＃34;表格由＆＃34; contactreply＆＃34;表。＆＃34; contactid＆＃34;排在＆＃34; contactreply＆＃34; table是＆＃34; ID＆＃34;排在＆＃34;联系人＆＃34;表。＆＃34;联系＆＃34;必须通过表格中的最后一个插入来排序＆＃34; contactreply＆＃34; ＆＃34; contactid＆＃34;是＆＃34; ID＆＃34;在表格中＆＃34;联系＆＃34;。

联系表：

+----+--------+----------+----------+
| ID | userid | subject  | content  |
+----+--------+----------+----------+
|  1 |      1 | subject  | subject  |
|  2 |      1 | subject2 | subject2 |
+----+--------+----------+----------+

回复表

+----+--------+-----------+---------+
| ID | userid | contactid | content |
+----+--------+-----------+---------+
|  1 |      1 |         1 | reply1  |
|  2 |      1 |         2 | reply2  |
|  3 |      1 |         1 | fasd    |
|  4 |      1 |         2 | asdf    |
|  5 |      1 |         2 | f       |
|  6 |      1 |         1 | asdf    |
+----+--------+-----------+---------+

我尽力解释它并希望你理解它;）我已经看过其他帖子，但我无法让它发挥作用。

提前谢谢。

Answer 1

检查这是否符合预期

select a.*, b.id from contact as a 
        inner join 
(select * from contactReply as x 
 where x.id = 
           (select max(id) from contactReply as y 
             where x.contactid = y.contactid)
 ) as b
on a.ID = b.contactId 
order by b.id

Answer 2

SELECT c.* 
  FROM contacts c 
  JOIN reply x 
    ON x.contactid = c.id 
  JOIN 
     ( SELECT MAX(id) max_id FROM reply GROUP BY contactid ) y 
    ON y.max_id = x.id 
 ORDER 
    BY x.id;
+----+--------+----------+----------+
| ID | userid | subject  | content  |
+----+--------+----------+----------+
|  2 |      1 | subject2 | subject2 |
|  1 |      1 | subject  | subject  |
+----+--------+----------+----------+

Sql按其他表选择顺序

2 个答案: