題目描述:
統計出當前各個title類型對應的員工當前(to_date=‘9999-01-01’)薪水對應的平均工資。結果給出title以及平均工資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);
解題思路:
在分組的是用Title進行分組
代碼:
select t.title , avg(s.salary)
from titles as t inner join salaries s
on t.emp_no = s.emp_no
and
t.to_date='9999-01-01'
and
s.to_date='9999-01-01'
group by title
輸出描述: