User Variable

[jongse park]

Hi,

How to tune the index for user variable?

mysql> set @a=10;
mysql> explain select col1, col2, count(col2)
from table1
where a=@a and col1='9.3'
group by col1, col2
order by col2;

How can I increase performance this query?
make index (a, col1, col2) ?
or don't pass a user variable in the where clause?
Can user variable use index ?

Please help me.