So I have two tables in my MySQL, users and purchases.
User table contains Id, Name, Surname and so on. Purchase table contains Id, User_id, Status and Sum payed for something.
What I need is to get select from these two tables where I would have the sum of every item each user has buyed.
I've tried this with table 'users':
LEFT JOIN 'purchases'
ON 'users'.'id' = 'purchases'.'user_id'
SELECT SUM (sum) FROM 'users', 'purchases' WHERE 'purchases'.'status' = 'completed' AND 'purchases'.'user_id' = 'users'.'id'
Id: 1 Name: John
Id: 2 Name: Ann
Id: 10 Status: completed User_id: 1 Sum: 4.00
Id: 20 Status: completed User_id: 1 Sum: 8.00
Id: 30 Status: completed User_id: 2 Sum: 50.00
Id: 40 Status: completed User_id: 2 Sum: 100.00
Id: 1 Sum: 12.00
Id: 2 Sum: 150.00
First off, your submitted SQL was a mess, things were completely out of the conventional order, I'm not sure it would execute as presented. That said, this should do what you want, assuming I understand your desired output correctly:
SELECT users.id, users.name, users.surname, ROUND(SUM(purchases.sum),2) AS totalSum FROM purchases LEFT JOIN users ON users.id = purchases.user_id WHERE status='completed' GROUP BY users.name, users.surname ORDER BY users.id
The key aspect you were missing from your query was the
GROUP BY section, I added
ORDER BY for my own benefit on my fiddle, use it if you wish, or not.
Here's a fiddle I prepped for you prior to your posting of your sample data, the main answer has been given by others I see so I'm just posting this because I already did the work on it. http://sqlfiddle.com/#!9/8fa2d/6/0
Fiddle is acting up so this is untested but give it a try.
SELECT users.id, users.name, users.surname, ROUND(SUM(CASE WHEN purchases.status = 'completed' THEN purchases.sum ELSE 0 END),2) AS totalSum FROM users LEFT JOIN purchases ON users.id = purchases.user_id GROUP BY users.id ORDER BY users.id