SQL16 - 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

题目描述:

统计出当前(titles.to_date='9999-01-01')各个title类型对应的员工当前(salaries.to_date='9999-01-01')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);

 

难易程度:

中等

 

解答:

select titles.title,avg(salaries.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