題目:
Employee 表包含所有員工,他們的經理也屬於員工。每個員工都有一個 Id,此外還有一列對應員工的經理的 Id。
+----+-------+--------+-----------+
| Id | Name | Salary | ManagerId |
+----+-------+--------+-----------+
| 1 | Joe | 70000 | 3 |
| 2 | Henry | 80000 | 4 |
| 3 | Sam | 60000 | NULL |
| 4 | Max | 90000 | NULL |
+----+-------+--------+-----------+
給定 Employee 表,編寫一個 SQL 查詢,該查詢可以獲取收入超過他們經理的員工的姓名。在上面的表格中,Joe 是唯一一個收入超過他的經理的員工。
+----------+
| Employee |
+----------+
| Joe |
+----------+
思路一:我先查出員工爲經理的工資,再和一般員工比較
select Name AS Employee from Employee as a
where Salary >(select Salary from Employee where Id=a.ManagerId);
思路二:
select A.Name AS Employee from Employee A,Employee B
where A.ManagerId=B.Id and A.Salary>B.Salary;