牛客SQL題解 - 統計出當前各個title類型對應的員工當前薪水對應的平均工資

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);

輸出描述

title	avg
Engineer	94409.0
Senior Engineer	69009.2
Senior Staff	91381.0
Staff	72527.0

試題詳解

連接salaries表和titles表並通過title字段group by，使用AVG聚合函數求均值。代碼如下：

SELECT title,AVG(salary) AS avg
FROM salaries AS s,titles AS t
WHERE s.emp_no = t.emp_no
AND s.to_date = '9999-01-01'
AND t.to_date = '9999-01-01'
GROUP BY t.title;