MySQL 8.0

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CREATE TABLE test (
    bucket int(10) NOT NULL,
    label varchar(10) NOT NULL,
    amount int(10) NOT NULL
);

INSERT INTO test VALUES
(1, "A", 1),
(1, "B", 2),
(1, "C", 3),
(2, "A", 4),
(2, "B", 5),
(2, "C", 6),
(3, "A", 7),
(3, "B", 8),
(3, "C", 9),
(4, "A", 10),
(4, "B", 11),
(4, "C", 12);
SELECT t.*,
       SUM(amount) OVER (PARTITION BY label 
                         ORDER BY amount
                        ) AS running_total
FROM test t
ORDER BY bucket, amount;


bucket
label
amount
running_total


1
A
1
1

1
B
2
2

1
C
3
3

2
A
4
5

2
B
5
7

2
C
6
9

3
A
7
12

3
B
8
15

3
C
9
18

4
A
10
22

4
B
11
26

4
C
12
30


SELECT t.*,
       SUM(amount) OVER (PARTITION BY label 
                         ORDER BY bucket, amount
                        ) AS running_total
FROM test t
ORDER BY bucket, amount;


bucket
label
amount
running_total


1
A
1
1

1
B
2
2

1
C
3
3

2
A
4
5

2
B
5
7

2
C
6
9

3
A
7
12

3
B
8
15

3
C
9
18

4
A
10
22

4
B
11
26

4
C
12
30