1.leetcode-184：查找部门内最高的薪水

首先是一个子查询，找出一个部门里最高的那个工资


随后查找最终需要的值，并且部门编号以及薪水应该包含在这个子查询中
最终答案：

# Write your MySQL query statement below
SELECT Department.name AS Department,Employee.name AS Employee,Salary
FROM Employee INNER JOIN Department 
ON Employee.departmentId = Department.id
WHERE (Employee.DepartmentId,Salary) IN( SELECT DepartmentId,MAX(Salary)FROM EmployeeGROUP BY DepartmentId);

2.leetcode-607 销售员（两次子查询）

# Write your MySQL query statement below
SELECT name 
FROM SalesPerson AS S
WHERE S.sales_id NOT IN (SELECT sales_idFROM OrdersWHERE Orders.com_id = ( SELECT com_idFROM CompanyWHERE Company.name = 'RED')
);

3.leetcode-585. 2016年的投资

# Write your MySQL query statement below
# roound(,2)四舍五入保留两位小数
SELECT round(SUM(Insurance.tiv_2016),2) AS tiv_2016
FROM  Insurance
WHERE Insurance.tiv_2015 IN ( SELECT tiv_2015FROM Insurance GROUP BY tiv_2015HAVING COUNT(tiv_2015 ) >=2)
AND CONCAT(Insurance.lat,' ',Insurance.lon) IN (  SELECT CONCAT(lat,' ',lon) FROM InsuranceGROUP BY lat,lonHAVING COUNT(*)=1);