题目描述
统计出当前各个title类型对应的员工当前薪水对应的平均工资。结果给出title以及平均工资avg。
CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));
CREATE TABLE IF NOT EXISTS "titles" (
`emp_no` int(11) NOT NULL,
`title` varchar(50) NOT NULL,
`from_date` date NOT NULL,
`to_date` date DEFAULT NULL);
输出描述
title
avg
Engineer
94409.0
Senior Engineer
69009.2
Senior Staff
91381.0
Staff
72527.0
解题方案
本题重点考查了两表关联之后如何进行排序，注意标注出来哪个字段属于哪个表即可。
select title,avg(salary)
from titles left join salaries
on titles.emp_no = salaries.emp_no
where titles.to_date='9999-01-01'
and salaries.to_date='9999-01-01'
group by titles.title
