Hello,
we have a position name in database like ‘Technician, Instrument & Electronics’
Now
$query_sal="SELECT * FROM salary_scale WHERE position='$position_name'";
print $query_sal
out put
SELECT * FROM salary_scale WHERE position='technician, instrument ’
why it is not processing the & 
i am sorry, this is an ajax problem.
i found the problem now. actually the variable $position_name holds only the ‘technician, instrument’ part which was returned by an ajward post before the query.
This code in ajax file did the fix
params = params + "&position=" + encodeURIComponent(position);