leetcode高阶sql

LeetCode是一个在线的技术面试平台，提供了许多算法和数据结构的题目，同时也提供了许多SQL的题目。下面是一些LeetCode高阶SQL的例子：

1. 部门工资最高的员工

SELECT Department.Name as Department, Employee.Name as Employee, Salary
FROM Employee
JOIN Department ON Employee.DepartmentId = Department.Id
WHERE (DepartmentId, Salary) IN (
    SELECT DepartmentId, MAX(Salary)
    FROM Employee
    GROUP BY DepartmentId
)

2. 每门课程成绩都大于80分的学生姓名

SELECT s1.Student
FROM Scores s1
WHERE NOT EXISTS (
    SELECT *
    FROM Scores s2
    WHERE s1.Student = s2.Student AND s2.Score <= 80
)

3. 连续出现的数字

SELECT DISTINCT l1.Num as ConsecutiveNums
FROM Logs l1, Logs l2, Logs l3
WHERE l1.Id = l2.Id - 1 AND l2.Id = l3.Id - 1
AND l1.Num = l2.Num AND l2.Num = l3.Num