1393. Capital Gain/Loss mysql

https://leetcode.com/problems/capital-gainloss/?envType=study-plan&id=sql-i 

Capital Gain/Loss - LeetCode

select tb.stock_name, sum(price) as capital_gain_loss
from (select stock_name, IF(operation = "Buy" , price*(-1), price) as price from stocks) tb
group by stock_name;