MySQL Update table with sum value of another table - mysql

Question

I have a query that I can't seem to manipulate to work in a SUM function in MySQL:
Here is what I want:
UPDATE account_seeds AS a
INNER JOIN b AS b ON b.accountID = a.accountID AND a.areaID = b.areaID
INNER JOIN b_seed AS s ON s.buildingID = b.buildingID
INNER JOIN seed_class AS c ON c.seedID = s.seedID
SET a.amount = a.amount + SUM(s.amount)
WHERE b.status='active' AND a.seedID = s.seedID
Now it obviously won't let me use the SUM in the update without separating it. I have tried joining select queries but can't quite get my head around it. The basic premise being that I have multiple buildings(rows) that has a seed value that will increase total seeds of that type in the area for a particular account. Without the sum it only updates one of the buildings that has a matching seed value

Answer 1

UPDATE
account_seeds AS a
INNER JOIN
( SELECT b.accountID, b.areaID, s.seedID
, SUM(s.amount) AS add_on
FROM b AS b
INNER JOIN b_seed AS s
ON s.buildingID = b.buildingID
INNER JOIN seed_class AS c
ON c.seedID = s.seedID
WHERE b.status = 'active'
GROUP BY b.accountID, b.areaID, s.seedID
) AS g
ON g.accountID = a.accountID
AND g.areaID = a.areaID
AND g.seedID = a.seedID
SET
a.amount = a.amount + g.add_on ;

Answer 2

Maybe you can use a nested query:
UPDATE account_seeds AS a
INNER JOIN b AS b ON b.accountID = a.accountID AND a.areaID = b.areaID
INNER JOIN b_seed AS s ON s.buildingID = b.buildingID
INNER JOIN seed_class AS c ON c.seedID = s.seedID
SET a.amount = a.amount + (SELECT SUM(amount) FROM b_seed)
WHERE b.status='active' AND a.seedID = s.seedID
Can you try that?