183.从不订购的客户
题目
# Write your MySQL query statement below
SELECT Name AS Customers
FROM Customers LEFT JOIN Orders
ON Customers.Id = Orders.CustomerId
WHERE Orders.CustomerId IS NULL;
184. 部门工资最高的员工
题目
SELECT d.Name AS Department, e.Name AS Employee, e.Salary
FROM Department d, Employee e
WHERE e.DepartmentId = d.id
AND (e.Salary, e.DepartmentId) IN (SELECT max(Salary), DepartmentId
FROM Employee
GROUP BY DepartmentId);
185.部门工资前三高的员工
题目
解答
SELECT d.Name AS Department, e1.Name AS Employee, e1.Salary
FROM Employee e1, Department d
WHERE e1.DepartmentId = d.Id
AND 3 > (SELECT COUNT(DISTINCT e2.Salary)
FROM Employee AS e2
WHERE e1.Salary < e2.Salary
AND e1.DepartmentId = e2.DepartmentId) -- primary key只能是Department,不可以是Id
ORDER BY d.Name, Salary DESC;
我现在也不知道主键那里到底是为什么
196. 删除重复的电子邮箱
DELETE FROM Person
WHERE id NOT IN (SELECT need.id
FROM ((SELECT MIN(Id) as id
FROM Person
GROUP BY Email) AS need));
197.上升的温度
SELECT a.Id
FROM Weather a JOIN Weather b
ON a.Temperature > b.Temperature
AND DATEDIFF(a.RecordDate, b.RecordDate) = 1;