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[LeetCode 176] Second Highest Salary

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                 |
+---------------------+

Thoughts

  1. Second Highest => ORDER BY Salary LIMIT 1 OFFSET 1
  2. No Second Highest => IFNULL( res , NULL)
  3. Consider duplicates

Code

SELECT (
    IFNULL ((SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC LIMIT 1 OFFSET 1), NULL)
) AS SecondHighestSalary;

References