Update multiple rows with where clause in codeigniter

Question

I have a list of records from database, see the attachment. How can i insert a vat no for each record using student id(see leftmost column). Each record has a input field(see rightmost column).

Here is my view:

    <?php $attributes = array('id' => 'VATformAdd', 'name' => 

'VATformAdd', 'autocomplete' => 'off'); echo form_open('report/addVATno', $attributes);?>
<fieldset>
<legend>Income By Student Admission</legend>
<table class="">
<thead>
<tr>
<th width="15%">Student ID</th>
<th width="15%">Student Form No</th>
<th width="15%">Course</th>
<th width="20%">Student Name</th>
<th width="15%">Admitted by</th>
<th width="10%">Amount</th>
<th width="10%">VAT Serial No</th>
</tr>
</thead>

<tbody>
<?php
    if (isset($addmission_income)) {
        foreach ($addmission_income as $addmissionincome) {
?>
<tr>
    <td><?php echo $addmissionincome->student_id;?></td>
    <td><?php echo $addmissionincome->student_form_no;?></td>
    <td><?php echo $addmissionincome->course_name;?></td>
    <td><?php echo $addmissionincome->student_full_name;?></td>
    <td><?php echo user_profile_name($addmissionincome->student_added_by); ?></td>
    <td><?php echo $addmissionincome->student_fee_paid;?></td>
    <td><input type="text" name="vatno[<?php echo $addmissionincome->student_id;?>]" class="width-100"/></td>
<?php       
        }
?>
</tr>
<?php       
    }
?>
</tbody>
</table>

<p>
<input id="submit" name="submit" type="submit"  value="Add VAT Number" />
</p>

</fieldset>
<?php echo form_close();?>

Here is my controller:

function addVATno(){
        $studentid = $this->input->post('studentid');
        foreach($studentid as $a){
            if($val[$a]!=''){
                $this->report_mdl->addVATno($a);
            }
        }
    }

Here is Model:

function addVATno($a){
        $val = $this->input->post('vatno');
        $updatevatsl = array( 
            'dupVATserial_no' => $val);
        $this->db->where('student_id', $a);
        $query = $this->db->update('data_student_master', $updatevatsl);
        return $query;
    }

Answer 1

make your view file with a hidden student_id like:

<input type="hidden" name="student_id[]" value="<?php echo $addmissionincome->student_id;?>"/>

and vatno field:

<input type="text" name="vatno[]" class="width-100"/>

Adding the following to your controller will do everything you need (without needing to put any code in your model):

  $student_id = $this->input->post('student_id');
  $vatno = $this->input->post('vatno');

  for ($i = 0; $i < count($student_id); $i++) {
        $sm_data[] = array(
            'vatno' => $vatno[$i],
            'student_id' => $student_id[$i]
        );
  }

$this->db->update_batch('data_student_master', $sm_data, 'student_id');

Note: It would be better to move the db call to your model to adhere to MVC conventions.