基本SQL和，选择，位置，GROUP BY语句

Question

I'm currently working on this data.

What should be resulting:

What should be produced is the result at the bottom of that picture.

Instead, I'm getting the result:

My code is the following:

SELECT distinct(username) as 'Name', p.price as 'Price', p.quantity as 'Quantity', (p.price * p.quantity) as 'Total'
 FROM users u, purchase p
WHERE u.userID = p.userID 
ORDER BY (username) asc  ; 

I am wondering how would I go about adding up the unique usernames (Alice's 4 and 1.5 to produce 5.5) and how do I also get Matt's name to display on the data?

Answer 1

Just minor changes, but the important thing is to group by user and not order by user

SELECT username as 'Name', SUM(p.price * p.quantity) as 'Total'
 FROM users u, purchase p
WHERE u.userID = p.userID 
GROUP BY username; 

Answer 2

从[用户]中选择u.name，总和（数量*价格）u左加入u.name对u.id = p.userId组购买p