如何找到特定的员工总金额

我有一张员工桌.此表有三列:CustomerName,Role,和Salary.在CustomerNameUser1列中出现多次,但我只想要一行总薪水为User1.下面我粘贴了一些样本数据供参考.

+--------------+------------+--------+
| CustomerName |    Role    | Salary |
+--------------+------------+--------+
| User1        | Design     |    100 |
| User2        | Developer  |    100 |
| User1        | Design     |    100 |
| User3        | Programmer |    100 |
| User1        | Design     |    100 |
+--------------+------------+--------+

输出应该像:

+--------------+------------+----------+
| CustomerName |     Role   |  Salary  |
+--------------+------------+----------+
| user1        | Design     |      300 |
| user2        | Developer  |      100 |
| user3        | Programmer |      100 |
+--------------+------------+----------+

我想要User1的工资总额.怎么能实现这一目标？

使用group by聚合

select customername,role, sum(salary) as salary
from tablename
group by customername, role