MYSQL GROUP BY and SUM with clause - mysql

Question

Hello there are two tables
Interval
id
is_full
1
1
2
0
3
0
entry_penalty
interval_id
entry_id
amount
2
14
55
3
14
7
3
14
1
1
15
4
1
15
8
2
15
11
So i am trying to display Sum of all entry_penalties per interval, twist is even if there is no relation between entry_penalty and interval table i should display full course interval sum per entry_id (related to is_full field).
For example total results should be in this case
interval_id
entry_id
amount
1
14
63
2
14
55
3
14
8
1
15
23
2
15
11
I have tried with sub query but it ignores to do calculation when there is no relation between entry_penalties and interval tables regarding is_full column.
My code so far.
SELECT
ep.interval_id,
IF (
i.is_full,
(
SELECT SUM(ep2.amount) * 1000 FROM entry_penalty as ep2
WHERE ep2.entry_id = ep.entry_id
),
SUM(ep.amount) * 1000
) as penalty_time,
ep.entry_id
FROM entry_penalty ep
INNER JOIN \`interval\` i ON i.id = ep.interval_id
WHERE ep.entry_id IN (:entryIds)
GROUP BY interval_id, entry_id`

Answer 1

I would propose to deal with the two cases (full, not full) separately, and then use union all to combine the two results:
SELECT i.id, ep.entry_id, SUM(ep.amount)
FROM `interval` i,
entry_penalty ep
WHERE i.is_full
GROUP BY i.id, ep.entry_id
UNION ALL
SELECT i.id, ep.entry_id, SUM(ep.amount)
FROM entry_penalty ep
INNER JOIN `interval` i
ON ep.interval_id = i.id
AND NOT i.is_full
GROUP BY i.id, ep.entry_id
ORDER BY 2, 1
See it run on dbfiddle.uk, where it outputs:
id
entry_id
SUM(ep.amount)
1
14
63
2
14
55
3
14
8
1
15
23
2
15
11