mysql中过滤分组where和having的区别
例子1
having的使用例子:
where的使用例子:
select dept_name ,sex,height from student_test where
height>150;
分析:
例子2
having例子的使用:
select dept_name,sex from student_test having height>150;
ERROR 1054(42S22):unknown column height in having clause.
where例子的使用:
select dept_name,sex from student_test where height>150;
分析:
例子3
having例子的使用:
select group_concat(dept_name),sex,height from student_test group by height having avg(height)>170;
where的使用例子: