SQLGrammarException: could not execute query

The SQLGrammarException is thrown because the SQL query generated by Hibernate has wrong SQL syntax. The way you built the query is wrong, you shouldn't concatenate values (especially string values) to the result query, because such code is vulnerable for possible SQL injection attack. Instead, you can use parameters in the query string

String empId = p.getEmpId();
String paramValue = "";
if (empId !=null && !empId.isEmpty())
    paramValue = " where b.empId=:empId";
String empName = p.getEmployeeName();
if (empName !=null && !empName.isEmpty()) {
    if (paramValue == "")
     paramValue =" where b.employeeName=:empName";
     paramValue =paramValue + " and b.employeeName=:empName"; 
Query query = session.createQuery("from RequestBean b"+paramValue);
//now set parameter values
if(empId !=null && !empId.isEmpty())
  query.setParameter("empId", empId);
if(empName !=null && !empName.isEmpty())
  query.setParameter("empName", empName);
recList = (List<RequestBean>) query.list();