ungroup SUM and GROUP BY

Question

I know how to do a SUM in MySQL but how add a column like this (ungroup the group ?)

CREATE TABLE Table1
    (`id` int, `price` int)
;

INSERT INTO Table1
    (`id`, `price`)
VALUES
    (1,10),
    (1, 10),
    (2, 20),
    (2, 20),
    (3, 30),
    (3, 31)
;

ID would be think like a 'category ID'. I want this :

ID    price    sum
--------------------
 1     10      20 <- or nothing if it's not to hard
 1     10      20
 2     20      40 
 2     20      40
 3     30      61
 3     31      61

Not this :

ID    price    sum
--------------------
 1     10      20
 2     20      40
 3     30      61

sql :

SELECT id, SUM(price)FROM Table1 GROUP BY id

http://sqlfiddle.com/#!2/34fbe/1

Answer 1

You can use a subquery:

select t.*, tt.sumprice
from table1 t join
     (select id, sum(price) as sumprice
      from table1 t
      group by id
     ) tt
     on t.id = tt.id;