您好我需要帮助我的MYSQL查询
我有桌子
id | tn | title | customer_id |create_time | comment |
1 | 1342 | sample1 | customer1 | 2012-01-01 | hello world |
2 | 1342 | sample1 | customer1 | 2012-01-02 | hello world |
3 | 1342 | sample1 | customer1 | 2012-01-03 | hello new world |
4 | 3362 | sample2 | customer1 | 2012-01-02 | good bye world |
5 | 3362 | sample2 | customer1 | 2012-01-03 | good bye world |
6 | 3362 | sample2 | customer1 | 2012-01-04 | good bye world |
7 | 3362 | sample2 | customer1 | 2012-01-05 | good bye new world |
当我分组tn 时,我接受了
1 | 1342 | sample1 | customer1 | 2012-01-01 | hello world |
4 | 3362 | sample2 | customer1 | 2012-01-02 | good bye world |
但我需要
3 | 1342 | sample1 | customer1 | 2012-01-03 | hello new world |
7 | 3362 | sample2 | customer1 | 2012-01-05 | good bye new world |
就像用最大id或最大create_time
分组tn一样我该怎么做?谢谢!
答案 0 :(得分:2)
试试这个:
mysql> select * from ( select * from tbl2 tn order by id desc ) t group by tn;
+------+------+---------+-------------+-------------+--------------------+
| id | tn | title | customer_id | create_time | comment |
+------+------+---------+-------------+-------------+--------------------+
| 3 | 1342 | sample1 | customer1 | 2012-01-03 | hello new world |
| 7 | 3362 | sample2 | customer1 | 2012-01-05 | good bye new world |
+------+------+---------+-------------+-------------+--------------------+
2 rows in set (0.02 sec)
答案 1 :(得分:1)
SELECT t2.* FROM
(SELECT MAX(id) AS id,tn FROM my_table GROUP BY tn) AS t1
LEFT JOIN my_table AS t2 USING(id)
答案 2 :(得分:0)
试试这个
Select t.* from
table t right join
(Select max(id) as max_id from table group by tn) t1 on (t.id=t1.max_id)