力扣sql中等篇练习(一)

1 第二高的薪水

1.1 题目内容

1.1.1 基本题目信息

1.1.2 示例输入输出

1.2 示例sql语句

SELECT IFNULL(
    (
        SELECT distinct salary SecondHighestSalary
        FROM Employee
        ORDER BY salary desc
        limit 1,1
    ),null
) SecondHighestSalary

1.3 运行截图

2 分数排名

2.1 题目内容

2.1.1 基本题目信息

2.1.2 示例输入输出

2.2 示例sql语句

# dense_rank()是密集排序的,不会有重复的
SELECT  score,dense_rank() over(order by Score desc) `rank`
FROM Scores 

2.3 运行截图

3 部门工资最高的员工

3.1 题目内容

3.1.1 基本题目信息

3.1.2 示例输入输出

3.2 示例sql语句

# Write your MySQL query statement below
SELECT d.name Department,e1.name Employee,e1.salary
FROM
Employee e1
INNER JOIN
(
  SELECT departmentId,MAX(salary) s
  FROM Employee  
  GROUP BY departmentId
) e2
ON  e1.departmentId=e2.departmentId AND e1.salary=e2.s
INNER JOIN Department d
on e1.departmentId=d.id

3.3 运行截图