Question

So, I’ve got a mysql query that looks like this:

SELECT rewards.name, redemptions.points, redemptions.value
FROM rewards
INNER JOIN redemptions ON rewards.id = redemptions.reward_id;

The problem is that it spits out a table like this:

-----------------------------
| Reward 1 |  500   |  30   |
-----------------------------
| Reward 1 |  500   |  30   |
-----------------------------
| Reward 1 |  500   |  30   |
-----------------------------
| Reward 2 |  100   |  10   |
-----------------------------
| Reward 2 |  100   |  10   |
-----------------------------
| Reward 3 |  250   |  20   |
-----------------------------

and so on. Ideally, what I would actually like it to do is to only list each one once, but sum certain columns. So for example, it would look something like this:

-----------------------------
| Reward 1 |  500   |  90   |
-----------------------------
| Reward 2 |  100   |  20   |
-----------------------------
| Reward 3 |  250   |  20   |
-----------------------------

Where it is summing the third column, but listing the first two columns just once. I thought maybe a union would do it because I know it ignores duplicates, but I don’t think it works while using unions as well.

Answer 1

Use SUM, and remember to add GROUP BY:

SELECT rewards.name, redemptions.points, SUM(redemptions.value)
FROM rewards
INNER JOIN redemptions ON rewards.id = redemptions.reward_id
GROUP BY rewards.name;