MySQL 分组之后 HAVING(条件)

查询工资总和大于9000的部门的编号以及工资和

 SELECT deptno, SUM(sal) FROM employee GROUP BY deptno HAVING SUM(sal) > 9000;

+--------+----------+
| deptno | SUM(sal) |
+--------+----------+
|     20 | 10875.00 |
|     30 |  9400.00 |
+--------+----------+

HAVING和WHERE区别

• WHERE 对原表数据进行筛选
• HAVING 对过滤之后表进行筛选

书写MySQL的顺序

SELECT --> FROM --> WHERE --> GROUP BY --> HAVING --> ORDER BY --> LIMIT

查询工资大于1500的，工资总和大于6000的部门编号以及工资的和

 SELECT deptno, SUM(sal) FROM employee WHERE sal>1500 GROUP BY deptno HAVING SUM(sal) > 6000 ORDER BY SUM(sal);

+--------+----------+
| deptno | SUM(sal) |
+--------+----------+
|     20 |  8975.00 |
+--------+----------+