Question

I have had a read through a few of the other issues around joining on SQL Updates but haven’t been able to finalise a query.

System is all in MySQL (INNODB table structure)

We are wanting to update an amount in one table that will increase an amount based on 2 variables from another table. There are a few constraints that need to be checked in the update to make sure the variables from the second table match the keys in the table to be updated

UPDATE as1
SET as1.amount = as1.amount + (b1.workers * b1.level)
FROM account_stock AS as1
INNER JOIN building AS b1 ON as1.accountID = b1.accountID
INNER JOIN building_seed AS bs1 ON bs1.buildingID = b1.buildingID
WHERE bs1.stockID = as1.stockID
AND b1.accountID = as1.accountID
AND b1.locID = as1.locID
AND b1.status = active
AND b1.gTime > 0

It’s getting an error and I can’t pick it. Sorry if it is a simple question, all my SQL is self taught so some of the habits I have aren’t very good!

Answer 1

MySQL syntax for UPDATE is different. There is no FROM:

UPDATE 
    account_stock AS as1
  INNER JOIN building AS b1 ON as1.accountID = b1.accountID
  INNER JOIN building_seed AS bs1 ON bs1.buildingID = b1.buildingID

SET as1.amount = as1.amount + (b1.workers * b1.level)

WHERE bs1.stockID = as1.stockID
  AND b1.locID = as1.locID
  AND b1.status = active
  AND b1.gTime > 0 ;

  --- removed duplicate : 
  --- AND b1.accountID = as1.accountID

Also: is active a column or you meant to write?: AND b1.status = 'active'