数据库SQL实战

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);

输入描述:

无

输出描述:

titleavgEngineer94409.0Senior Engineer69009.2Senior Staff91381.0Staff72527.0

求平均值用avg()函数

select t.title, avg(s.salary) avgfrom titles t, salaries swhere t.emp_no = s.emp_noand t.to_date = '9999-01-01'and s.to_date = '9999-01-01'group by title