現在 Student表有 如下數據
現需求如下： 查找每個老師的學生的平均年齡且平均年齒大於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
使用HAVING
1 SELECT TeacherID, AVG(Age) AS AGE FROM Student 2 GROUP BY TeacherID 3 HAVING AVG(Age) > 12
結果如下：
HAVING:給分組設置條件