1、需求
user表
temp表
user_temp_salary表
1.1 查找每个人在2018年前2个月的平均工资信息
SELECT b.`name` AS userName,c.name AS tempName,aa.avgSalary
FROM `user` b
INNER JOIN
(SELECT a.user_id,FORMAT(avg(a.salary),2) AS avgSalary
FROM user_temp_salary a
WHERE a.`month`<3 AND a.`year`=2018
GROUP BY a.user_id) aa
ON b.id=aa.user_id
INNER JOIN temp c ON b.temp_id=c.id
执行结果：
1.2 找2018年每个部门、每个月的工资总和
SELECT aa.year,aa.month,b.name AS tempName,aa.sumSalary
FROM temp b
INNER JOIN
(SELECT a.year,a.month,a.temp_id,SUM(a.salary) AS sumSalary
FROM user_temp_salary a
WHERE a.year=2018
GROUP BY a.temp_id,a.month
ORDER BY SUM(a.salary) DESC) aa
ON b.id=aa.temp_id
执行结果：