Question

I have a table called credit_log and the columns are

user_id | amount

The amount can be positive or negative. Positive means credits bought, negative means credits spent.
So, I want to have a query which returns

user_id | Bought | Spent 

essentially , i want to sum up positive amount values in to Bought and sum up negative amount in to Spent and I want to group by the user_id

Currently I have a query like this

select user_id,sum(amount) from credit_log group by user_id;

but it sums up both positive and negative values. How can I write a query to separate them?

Answer 1

Some conditional statements inside the query should work nicely:

SELECT
    user_id,
    SUM(IF(amount > 0, amount, 0)) bought,
    SUM(IF(amount < 0, amount, 0)) spent
FROM credit_log
GROUP BY user_id;