mysql 取每组前几条记录
2016-01-04 10:30
567 查看
一、对分组的记录取前N条记录:例如:取每组的前3条最大的记录
1.用子查询:
SELECT * FROM tableName a WHERE 3>
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND b.cnt>a.cnt)
ORDER BY a.id,a.account DESC
2.用exists半连接:
SELECT * FROM tableName a WHERE EXISTS
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND a.account<b.cnt HAVING COUNT(*)<3)
ORDER BY a.id,a.cntDESC
二、同理可以取组内最小的N条记录:例如:取每组的前3条最小的记录
1、子查询
SELECT * FROM tableName a WHERE 3>
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND b.cnt<a.cnt)
ORDER BY a.id,a.cnt DESC
2、用exists:
SELECT * FROM tableName a WHERE EXISTS
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND a.cnt>b.cnt HAVING COUNT(*)<3)
ORDER BY a.id,a.cnt DESC
1.用子查询:
SELECT * FROM tableName a WHERE 3>
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND b.cnt>a.cnt)
ORDER BY a.id,a.account DESC
2.用exists半连接:
SELECT * FROM tableName a WHERE EXISTS
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND a.account<b.cnt HAVING COUNT(*)<3)
ORDER BY a.id,a.cntDESC
二、同理可以取组内最小的N条记录:例如:取每组的前3条最小的记录
1、子查询
SELECT * FROM tableName a WHERE 3>
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND b.cnt<a.cnt)
ORDER BY a.id,a.cnt DESC
2、用exists:
SELECT * FROM tableName a WHERE EXISTS
(SELECT COUNT(*) FROM tableName b WHERE b.id=a.id AND a.cnt>b.cnt HAVING COUNT(*)<3)
ORDER BY a.id,a.cnt DESC
相关文章推荐
- mysql数据导入、导出方法汇总
- 安装mysql
- mysql导入数据load data infile用法
- 如何修改mysql数据库编码
- mysql导出数据不输出标题行
- mysql导出数据中文乱码问题
- mysqldump导出时出现when doing LOCK TABLES
- mysql连接拒绝问题
- mysql操作命令记录
- MySql Host is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts' 解决方法
- mysql 多表联合更新
- MYSQL general tablespace
- mysql profile及其对应表使用
- MySQL5.6分区数量太多引发的血案
- MySQL的编码字符集问题
- MySQL错误:Another MySQL daemon already running with the same unix socket.
- MySQL的事务处理及隔离级别
- MySql语法大全(速成版)
- Mysql学习总结(11)——MySql存储过程与函数
- Mysql学习总结(10)——MySql触发器使用讲解