LeetCode题解(0579)：查询员工的累计薪水(SQL)

题目：原题链接（困难）

标签：SQL

解法	时间复杂度	空间复杂度	执行用时
Ans 1 (Python)			336ms (22.34%)
Ans 2 (Python)
Ans 3 (Python)

解法一：

SELECT E1.Id AS Id,
       E1.Month AS Month,
       (IFNULL(E1.Salary, 0) + IFNULL(E2.Salary, 0) + IFNULL(E3.Salary, 0)) AS Salary
FROM Employee AS E1
         LEFT JOIN
     Employee AS E2 ON (E2.Id = E1.Id AND E2.Month = E1.Month - 1)
         LEFT JOIN
     Employee AS E3 ON (E3.Id = E1.Id AND E3.Month = E1.Month - 2)
WHERE (E1.Id, E1.Month) NOT IN (SELECT Id, MAX(Month)
                                FROM Employee
                                GROUP BY Id)
ORDER BY E1.Id, E1.Month DESC;