Given an SQL table

ID Amt
-- ---
1 100
2 200
3 300

Please write a MySQL statement to produce the following result:

ID Amt Total
-- --- -----
1  100 100
2  200 300
3  300 600

And here is an example SQL:

SELECT a.ID, a.Amt, sum(b.Amt) AS Total
FROM tab AS a
JOIN tab AS b ON a.ID >= b.ID
GROUP BY 1,2