update multiple data codeigniter with checkbox

Question

I am trying to update multiple data through AJAX but I have tried several times, but the data has not changed, please help to fix it in order to run perfectly.

Controllers:

function update_notif() {
    $this->My_model->update_multiple();
    $this->session->set_flashdata('msg', 
                '<div class="callout callout-warning">
                    <h4>Success</h4>
                </div>');                   
}

Models:

function update_multiple() {
    $update = $this->input->post('id_pesan');
    for ($i=0; $i < count($update) ; $i++) { 
        $data = array('notif' => 0);            
        $this->db->where('id', $delete[$i]);
        $this->db->update('my_table', $data);               
    }
}   

Views:

<button type="button" id="btn_delete" ></button>

<table class="table table-hover table-striped">
    <thead>
        <tr>
            <td><input id="selecctall" type="checkbox"></td>
            <td>No</td>
            <td>Name</td>
            <td>Telp</td>
        </tr>
    </thead>
    <tbody>
        <?php foreach ($show_data as $row) { ?>
        <tr>
            <td><input type="checkbox" class="select_update" name="select_update[]" value="<?php echo $row->id; ?>"></td>
            <td><?php echo $row->no; ?></td>
            <td><?php echo $row->nama; ?></td>
            <td><?php echo $row->telp; ?></td>
        </tr>   
    </tbody>
    <?php } } ?>
</table>    

Ajax:

var getVar = [];  
$(".select_update:checked").each(function() {  
        getVar.push($(this).val());
}); 

$.ajax({
    url : url,
    type: 'POST',
    data: 'id_pesan='+getVar,
    dataType: 'json',
    success: function(response)
    {
        if(response){
            location.reload();
        }           
    },
    error: function (jqXHR, textStatus, errorThrown)
    {
        alert('Error');
    }
 });

Answer 1

How does your Ajax looks like?
I think you have to change

$update = $this->input->post('select_id');

into

$update = $this->input->post('select_update'); or $this->input->post('select_update[]');

because of the name attribute of your checkboxes and change

$this->db->where('id', $delete[$i]);

into

$this->db->where('id', $update[$i]);

or use it in a foreach

function update_multiple() {
    $updates = $this->input->post('select_update');

    foreach ($updates as $update) { 
        $data = array('notif' => 0);            
        $this->db->where('id', $update);
        $this->db->update('my_table', $data);               
    }
}   

Update #1

Your Ajax should look like this - keep scope on data of ajax

$.ajax({
  url : url,
  type: 'POST',
  data: $(".select_update:checked").serialize(),
  dataType: 'json',
  success: function(response) { ... },
  error: function (jqXHR, textStatus, errorThrown) { ... }
});

Answer 2

It seems you have pasted your code from your delete_multiple method and this is why you use $delete instead of $update here

function update_multiple() {
    $update = $this->input->post('select_id');
    for ($i=0; $i < count($update) ; $i++) { 
        $data = array('notif' => 0);            
        $this->db->where('id', $delete[$i]);
        $this->db->update('my_table', $data);               
    }
}

Solution:

function update_multiple() {
    $update = $this->input->post('select_id');
    for ($i=0; $i < count($update) ; $i++) { 
        $data = array('notif' => 0);            
        $this->db->where('id', $update[$i]);
        $this->db->update('my_table', $data);               
    }
}

Inspired from UfguFugullu, who was apparently inspired by my answer as well:

select_update is needed instead of select_id