select from sqlce database with c#

SqlCeConnection JSS_cnn05 = new SqlCeConnection();
           JSS_cnn05.ConnectionString = Publics.jeus_Coonn;
           JSS_cnn05.Open();
           string JSS_check05 = "Select COUNT(*)FROM reg where reg_OK = '" + JSS_AUTH + "'";

           SqlCeCommand JSS_cd05 = new SqlCeCommand(JSS_check05, JSS_cnn05);
           JSS_cd05.CommandText = JSS_check05;
           int JSS_RowCount05 = (int)JSS_cd05.ExecuteScalar();
           if (JSS_RowCount05 == 0)
           {

               JSS_Regestation JSS_fr = new JSS_Regestation();
               JSS_fr.Show();
               this.Hide();
           }


           else
           {
               JSS_LOGIN JSS_fr = new JSS_LOGIN();
               JSS_fr.Show();
               this.Hide();
           }










           string JSS_connetionString001 = null;
           SqlCeConnection JSS_cnn001;
           SqlCeCommand JSS_cmd001;
           string JSS_sql001 = null;
           SqlCeDataReader JSS_reader001;
           JSS_connetionString001 = Publics.jeus_Coonn;
           JSS_sql001 = "select * from product_companies where prodc_ID=select max(prodc_ID) from product_companies)";
           JSS_cnn001 = new SqlCeConnection(JSS_connetionString001);
           try
           {
               JSS_cnn001.Open();
               JSS_cmd001 = new SqlCeCommand(JSS_sql001, JSS_cnn001);
               JSS_reader001 = JSS_cmd001.ExecuteReader();
               while (JSS_reader001.Read())
               {
                   label4.Text = (JSS_reader001.GetValue(0) + "");
               }
               JSS_reader001.Close();
               JSS_cmd001.Dispose();
               JSS_cnn001.Close();
           }
           catch (Exception ex)
           {
               return;
           }