SQL 中 HAVING 用法

现在 Student表有如下数据

现需求如下：查找每个老师的学生的平均年龄且平均年齿大于12

不使用 HAVING

1 SELECT * FROM (SELECT TeacherID, AVG(Age) AS AGE FROM Student
2   GROUP BY TeacherID) T WHERE T.AGE > 12

View Code

使用HAVING

1   SELECT TeacherID, AVG(Age) AS AGE FROM Student
2   GROUP BY TeacherID
3   HAVING AVG(Age) > 12

View Code

结果如下：

HAVING:给分组设置条件

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原文地址：https://www.cnblogs.com/lao-tang/p/6398577.html