Que raro jurena.
Acabo de hacerlo y no me presenta problema por el campo. Debe ser cuestión de la versión de mysql. No noto ninguna diferencia entre varchar y numerico para hacer uso de group_concat
Código consulta:
Ver originalmysql> desc tabla1;
+--------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| nombre | text | YES | | NULL | |
| puntos | float | YES | | NULL | |
| otro | bigint(20) | YES | | NULL | |
+--------+------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
mysql> select *from tabla1;
+------+----------------------+--------+-------------+
| id | nombre | puntos | otro |
+------+----------------------+--------+-------------+
| 2 | daniela | 150 | 23245353454 |
| 3 | danielito | 80 | 23245353454 |
| 4 | danielita | 60 | 23245353454 |
| 6 | daniela | 180 | 23245353454 |
| 5 | huesos | 30 | 256 |
+------+----------------------+--------+-------------+
7 rows in set (0.00 sec)
mysql> select id, group_concat(otro separator ',') from tabla1 group by id;
+------+----------------------------------+
| id | group_concat(otro separator ',') |
+------+----------------------------------+
| 2 | 23245353454 |
| 3 | 23245353454 |
| 4 | 23245353454 |
| 5 | 23245353454,23245353454,256 |
| 6 | 23245353454 |
+------+----------------------------------+
5 rows in set (0.01 sec)