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")