Evitaría usar otra mesa. Una sola consulta es suficiente.
create table mytable (
id int not null auto_increment primary key,
username varchar(50),
email varchar(50),
number int
) engine = myisam;
insert into mytable (username,email,number)
values
('a','aaa',10),
('b','bbb',30),
('c','ccc',50),
('d','ddd',30),
('e','eee',20),
('f','fff',45),
('g','ggg',20);
select @r:[email protected]+1 as rnk,username,email,number
from mytable,(select @r:=0) as r order by number desc
+------+----------+-------+--------+
| rnk | username | email | number |
+------+----------+-------+--------+
| 1 | c | ccc | 50 |
| 2 | f | fff | 45 |
| 3 | b | bbb | 30 |
| 4 | d | ddd | 30 |
| 5 | e | eee | 20 |
| 6 | g | ggg | 20 |
| 7 | a | aaa | 10 |
+------+----------+-------+--------+
7 rows in set (0.00 sec)
Esta es una versión más inteligente que considera los lazos
select @r:[email protected] + 1 as rn, username,email,
@pos:= if(@previous<>number,@r,@pos) as position,
@previous:=number as num
from mytable,(select @r:=0,@pos:=0,@previuos:=0) as t order by number desc
+------+----------+-------+----------+--------+
| rn | username | email | position | num |
+------+----------+-------+----------+--------+
| 1 | c | ccc | 1 | 50 |
| 2 | f | fff | 2 | 45 |
| 3 | b | bbb | 3 | 30 |
| 4 | d | ddd | 3 | 30 |
| 5 | e | eee | 5 | 20 |
| 6 | g | ggg | 5 | 20 |
| 7 | a | aaa | 7 | 10 |
+------+----------+-------+----------+--------+
7 rows in set (0.00 sec)
