Ranking for unique users - mysql

Question

If I have three columns:
id, username, time
My data is:
+-------+------------------+-------------+
| id | username | time |
+-------+------------------+-------------+
| 1 | A | 1 min |
| 2 | A | 2 min |
| 3 | B | 3 min |
| 4 | B | 4 min |
+-------+------------------+-------------+
This query is working to get the ranking:
SELECT time,
FIND_IN_SET(MIN(time), (SELECT GROUP_CONCAT(time ORDER BY time ASC)
FROM table t1)) AS rank
FROM table t2
WHERE t2.username = 'B';
There is only one problem: It returns Rank 3de for the user B instead 2nd.
So I tried to use GROUP BY t2.username and also Distinct t2.username but did not work.
How can I get the rank of THE user B? It should be 2 (Not 3) because we have only 2 users.

Answer 1

E.g.:
DROP TABLE IF EXISTS my_table;
CREATE TABLE my_table
(id INT NOT NULL
,username CHAR(1) NOT NULL
,time TIME NOT NULL
);
INSERT INTO my_table VALUES
(1,'A','00:01:00'),
(2,'A','00:02:00'),
(3,'B','00:03:00'),
(4,'B','00:04:00');
SELECT * FROM my_table;
+----+----------+----------+
| id | username | time |
+----+----------+----------+
| 1 | A | 00:01:00 |
| 2 | A | 00:02:00 |
| 3 | B | 00:03:00 |
| 4 | B | 00:04:00 |
+----+----------+----------+
SELECT *
FROM
( SELECT username
, time
, #i:=#i+1 rank
FROM
( SELECT username
, MIN(time) time
FROM my_table
GROUP
BY username
) x
, (SELECT #i:=0) vars
ORDER
BY time
) n
WHERE username = 'B';
+----------+----------+------+
| username | time | rank |
+----------+----------+------+
| B | 00:03:00 | 2 |
+----------+----------+------+
I think this would work too, but it's slightly hacky, so I'm not sure...
SELECT x.*
, FIND_IN_SET(time,(SELECT GROUP_CONCAT(DISTINCT time ORDER BY time) FROM (SELECT MIN(time) time FROM my_table GROUP BY username) j )) rank
FROM my_table x HAVING rank <> 0 AND username = 'B';