SQL语句

SELECT user_name,COUNT(*) AS count FROM db_user_info GROUP BY user_name HAVING count > 1;

SELECT user_name FROM db_user_info GROUP BY user_name HAVING COUNT(1) > 1;

SELECT * FROM db_user_info WHERE user_name IN (SELECT user_name FROM db_user_info GROUP BY user_name HAVING COUNT(1) > 1);

• HAVING是分组（GROUP BY）后的筛选条件，分组后的数据组内再筛选；WHERE 则是在分组前筛选。
• WHERE 子句中不能使用聚集函数，而 HAVING 子句中可以，所以在集合函数中加上了 HAVING 来起到测试查询结果是否符合条件的作用。即 HAVING 子句的适用场景是可以使用聚合函数。

 

原p：https://www.cnblogs.com/wumz/p/10440123.html