Codeigniter checkbox value

I want the value that is depended on the checked of the user
1st checkbox = 1, 2nd checkbox = .5, 3rd checkbox .5 that will be inserted/updated to the players column name "player_attitude" if the user check 1st box and 3rd the value of the user will be 1.5 in column "player_attitude"

My table name is players with the columns
player_id,player_fname,player_address,player_attitude

Since the player is already registered i want to add/update player attitude of the user

This is my output

View

<form action="<?php echo base_url('Evaluations/update') ?>" method="POST">
             <?php foreach($evaluationlist as $players): ?>     
           <tbody>
             <tr>
               <td>&nbsp;&nbsp;<?php echo $players->player_lname?>&nbsp;,&nbsp;<?php echo $players->player_fname?> 
               </td>

               <td><center>
                <input type="checkbox" name="checkbox1" value="1">
              </center></td>

                <td><center>
                  <input type="checkbox" name="checkbox2" value=".5">
                </center></td>

                <td><center>
                  <input type="checkbox" name="checkbox3" value=".5">
                </center></td>        
                    <td></td>

               <td>
                <a href="<?php echo base_url('Players/editview/'.$players->player_id) ?>"><span class="b"><span class="glyphicon glyphicon-check">Manage</span></span></a>               
                </td>


             </tr>
           </tbody>

         <?php endforeach; ?>

Controller

public function update($player_id){
    $this->load->model('User_model');
    $this->User_model->checkIfLoggedIn();

    $this->load->view('incf/header');
    $this->load->view('evaluationf/ev_tools');

    $checkbox1 = $this->input->post('checkbox1');
    $checkbox2 = $this->input->post('checkbox2');
    $checkbox3 = $this->input->post('checkbox3');

    $player_attitude = $checkbox1+$checkbox2+$checkbox3;
    //print_r($player_attitude); exit();
    $this->load->model('Evaluation_model');


if($this->Evaluation_model->editview($player_id,$player_attitude)){
        $this->session->set_flashdata('message', [
            'status' => 'success',
            'message' => '&nbsp;<span class="glyphicon glyphicon-ok-circle"> Account Successfully Updated!</span>'
            ]);

        redirect(base_url('Players'));
    }else{
        $this->session->set_flashdata('message', [
            'status' => 'danger',   
            'message' => '&nbsp;<span class="glyphicon glyphicon-remove-circle"> Please try again.</span>'
            ]);

        redirect(base_url('Players'));
    }

}

Model

public function editview($player_id,$player_attitude){

    $data = [               
            'player_attitude' =>$player_attitude                
    ];

    $this->db->where('player_id',$player_id);
    return $this->db->update('players',$data);
}