题目

代码部分一（1095ms）

SELECT
    MAX(Salary) AS SecondHighestSalary
    FROM Employee E1
    WHERE 1=(SELECT COUNT(DISTINCT(E2.Salary)) FROM Employee E2 WHERE E2.Salary>E1.Salary);

代码部分二（222ms）

SELECT
    (SELECT DISTINCT Salary 
    FROM Employee
    ORDER BY Salary DESC
    LIMIT 1,1) AS SecondHighestSalary