[Leetcode] [Database] Second Highest Salary解題

題目如下

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 second highest salary is 200. If there is no second highest salary, then the query should return null.

題目意思: 選出數據中第二high的數據

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題目思路: 選出的所有比最大的數據少的數據，從中選出最大的數據

select max(Salary) 
    from Employee e 
        where e.Salary<(
            select max(Salary) from Employee);