MySQL的平均值和总数

分类: 技术问答 • 2022-04-03 14:31:35

MySQL的平均值和总数

问题描述：

这是我的代码，但所有值都相同。MySQL的平均值和总数

SELECT 
    department.name, 
    AVG(salary) AS Average, 
    SUM(salary) AS Total 
FROM 
    department, employee 
GROUP BY 
    department.name

querie

答

你缺少的表之间的连接状态，所以你把它们合并为一个完整的交叉产品，而不是员工只链接到他们的部门。

SELECT d.name, AVG(e.salary), SUM(e.salary) 
FROM department AS d 
JOIN employee AS e ON d.dpt_no = e.dpt_no 
GROUP BY d.name