How to bring various data according to your id in a modal

I have a modal that brings me the data of two tables according to their id, the problem is that I do not know how to make a for to print if there are more than a data according to the id, so far only brings me one.

code ...

PHP connection

    <?php  

    $connect = mysqli_connect("localhost", "root", "", "cargabilidad");  
   if(isset($_POST["employee_id"]))  
   {  
   $query = "SELECT * FROM sistema_rectificador,bateria WHERE id = 
   '".$_POST["employee_id"]."' and codigo=codigo_fk";  
   $result = mysqli_query($connect, $query);  
   $row = mysqli_fetch_assoc($result);  
   echo json_encode($row); 
   } else{
    echo "error";
   }
    ?>

MODAL

           <div id="add_data_Modal" class="modal fade">  
           <div class="modal-dialog">  
           <div class="modal-content">  
            <div class="modal-header">  
                 <button type="button" class="close" data- 
            dismiss="modal">&times;</button>  
                 <h4 class="modal-title">formulario-MODAL</h4>  
            </div>  
            <div class="modal-body"> 


                 <form method="post" id="insert_form" name="f1"> 



                 <input type="button" value="Bateria" name="codigo_fk" class="btn btn-md btn-warning" id="eli" > 
                 <div class="elim">
                      <label>Codigo</label>  
                      <input type="text" name="codigo_fk" id="codigo_fk" class="form-control" />  
                      <br />  
                      <label>Nemonico</label>  
                      <input type="text" name="nemonico" id="nemonico" class="form-control">  
                      <br />  
                      <label>Equipo</label>  
                      <input type="text" name="equipo_b" id="equipo_b" class="form-control">  
                      <br />  
                      <label>Marca</label>  
                      <input type="text" name="marca_b" id="marca_b" class="form-control" />  
                      <br />  
                      <label>Cargabilidad</label>  
                      <input type="text" name="cargabilidad" id="cargabilidad" class="form-control" />  
                      <br /> 
                       <label>Año Actual</label>  
                      <input type="text" name="ano_actual" id="ano_actual" class="form-control" />  
                      <br /> 
                      <label>Año Instalacion</label> 
                      <input type="text" name="ano_instalacion_b" id="ano_instalacion_b" class="form-control" />  
                      <br /> 
                      <label>Vida Util</label> 
                      <input type="text" name="vida_util_b" id="vida_util_b" class="form-control" />  
                      <br /> 
                      <label>Obsolescencia</label> 
                      <input type="text" name="obsolescencia_b" id="obsolescencia_b" class="form-control" />  
                      <br /> 
                      <label>Capacidad</label> 
                      <input type="text" name="capacidad_b" id="capacidad_b" class="form-control" />  
                      <br /> 

                      <input type="hidden" name="employee_id" id="employee_id" />   
                      <input type="submit" name="insert" id="insert" value="Insert" class="btn btn-success" /> 
              </div>


                 </form>  
               </div>
            </div>  
            <div class="modal-footer">  
                 <button type="button" class="btn btn-default" data-dismiss="modal">Salir</button>  
            </div>  
          </div> 
       </div>  
  </div>  

script

  $(document).ready(function(){  
  $('#add').click(function(){  
       $('#insert').val("Insert");  
       $('#insert_form')[0].reset();  
  });  
  $(document).on('click', '.edit_data', function(){  
       var employee_id = $(this).attr("id");  
       $.ajax({  
            url:"fetch2.php",  
            method:"POST",  
            data:{employee_id:employee_id},  
            dataType:"json",  
            success:function(data){  
                 $('#codigo_fk').val(data.codigo_fk);  
                 $('#nemonico').val(data.nemonico);  
                 $('#equipo_b').val(data.equipo_b);  
                 $('#marca_b').val(data.marca_b);  
                 $('#cargabilidad').val(data.cargabilidad);  
                 $('#ano_instalacion_b').val(data.ano_instalacion_b);  
                 $('#vida_util_b').val(data.vida_util_b);  
                 $('#obsolescencia_b').val(data.obsolescencia_b);  
                 $('#capacidad_b').val(data.capacidad_b);  
                 $('#employee_id').val(data.id);  
                 $('#codigo').val(data.codigo);  
                 $('#insert').val("Actualizar");  
                 $('#add_data_Modal').modal('show');  
            }  
       });  
  });  

  $(document).on('click', '.view_data', function(){  
       var employee_id = $(this).attr("id");  
       if(employee_id != '')  
       {  
            $.ajax({  
                 url:"select.php",  
                 method:"POST",  
                 data:{employee_id:employee_id},  
                 success:function(data){  
                      $('#employee_detail').html(data);  
                      $('#dataModal').modal('show');  
                 }  
            });  
       }            
  });  

});