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🎨 视觉封面LeetCode Second Highest Salary
Problem
Write a SQL query to get the second highest salary from the Employee table.
+----+--------+
| Id | Salary |
+----+--------+
| 1 | 100 |
| 2 | 200 |
| 3 | 300 |
+----+--------+
For example, given the above Employee table, the query should return 200 as the second highest salary. If there is no second highest salary, then the query should return null.
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200 |
+---------------------+
即找到第二大的元素。没有返回null。
MySQL
# Write your MySQL query statement below
SELECT (SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC LIMIT 1 OFFSET 1) AS SecondHighestSalary;
分析
通过LIMIT OFFSET找到第二个元素。DISTINCT是为了排除两个最大值的情况。嵌套是为了解返回null的情况。另一种办法是使用IFNULL函数。
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