Advanced search inJSP

I can only perform single search in JSP, how to correct the codes to perform advanced serach ?(ketword search of JobName and select the JobCategory)

Partial of the servlet:

        // obtain the parameter name;
        //  String jId = request.getParameter("jId");
        // String cId = request.getParameter("cId");
        String JobName = request.getParameter("JobName");
        String JobCategory = request.getParameter("JobCategory");
        if (JobCategory != null ) {
            ArrayList<JobInfo> byCat = db2.queryJobByCategory(JobCategory);
            request.setAttribute("jobs", byCat);
            JobCategory = "";
        } else if  ( JobName != null) {
            ArrayList<JobInfo> byName = db2.queryJobByName(JobName);
            request.setAttribute("jobs", byName);
            JobName = "";
        }
        RequestDispatcher rd;
        rd = getServletContext().getRequestDispatcher("/studentListJob.jsp");
        rd.forward(request, response);
    } else {
        PrintWriter out = response.getWriter();
        out.println("No such action!!!");
    }

Database :

     try {
        cnnct = getConnection();
        String preQueryStatement = "SELECT * FROM job WHERE JobName LIKE ? ";

        pStmnt = cnnct.prepareStatement(preQueryStatement);
        pStmnt.setString(1, JobName + "%");
        ResultSet rs = null;
        rs = pStmnt.executeQuery();

        while (rs.next()) {
            cb = new JobInfo();

            cb.setJobName(rs.getString("JobName"));
            cb.setJobCategory(rs.getString("JobCategory"));
            jobs.add(cb);

        }
        pStmnt.close();
        cnnct.close();

    } catch (SQLException ex) {
        while (ex != null) {
            ex.printStackTrace();
            ex = ex.getNextException();
        }
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    return jobs;

}

Seach by JobCategory:

    try {
        cnnct = getConnection();
        String preQueryStatement = "SELECT * FROM job WHERE JobCategory=? ";
        pStmnt = cnnct.prepareStatement(preQueryStatement);
        pStmnt.setString(1, JobCategory  );
        ResultSet rs = null;
        rs = pStmnt.executeQuery();

        while (rs.next()) {
            cb = new JobInfo();
             //String jId = rs.getString("jId");
           // String cId = rs.getString("cId");
            String JobName = rs.getString("JobName");
          //  cb.setjId(jId);
           //   cb.setcId(cId);
            cb.setJobName(JobName);
            cb.setJobCategory(JobCategory);
            jobs.add(cb);

        }
        pStmnt.close();
        cnnct.close();

    } catch (SQLException ex) {
        while (ex != null) {
            ex.printStackTrace();
            ex = ex.getNextException();
        }
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    return jobs;

}