collection_select

Hi,
      i am using one collection select in my application,
      and i am trying to set the value which i am selected,but i
      unable to fixed it.It always refer to first value.Here is my
      code,what is wrong in this code,
      and what is the appropriate code.please help.

     <%= collection_select(:employeedetails, :EmpNo,
@emprecord,:EmpNo,:Employee_Name,{:selected=>Employee_Name},{:class =>
"abc"})%>
   and in controller::
  @emprecord=EmployeeDetails.find_by_sql("select * from
EmployeeDetails")