mysql>查询语句_MySQL

mysql >查询语句

* 查询多条不重复记录

id name

1 a

2 b

3 c

4 c

5 b

select id, name from s1 group by name

1 a

2 b

3 c

5 b

* 查询重复记录最多的记录

SELECT keyword, count( * ) AS count

FROM article_keyword

GROUP BY keyword

ORDER BY count DESC

LIMIT 20

* 查询重复记录和重复次数

select user_name,count(*) as count from user_table group by user_name having count>1;

* 多联查询

s1表

id name

3 a

s2表

id s1_id age

1 2 12

2 3 23

SELECT * FROM `s2` WHERE `s1_id` = (SELECT id FROM `s1` WHERE `name` = 'a');

结果

2 3 23