CodeIgniter update_batch without replacing the pre

Although I am not sure. update_batch is it possible to without replacing the previous data next updated value will puts by comma separated as an array-form on the SAME FILED . I shown 2 Demo image for better understand. My Code is already running for only batch update But not for update_batch increment value without replacing previous data!

For example - For 1st time update , column field will shown like this at "t_franchise_price" column ---

For 2nd time When next update will perform , then column field "t_franchise_price" will look like this ---

My Controller is

public function batch_update() {

    $sID = $this - > input - > post('test_id[]');
    $sAmt = $this - > input - > post('test_priceUpdt[]');
    $sOfficeId = $this - > input - > post('fran_office_id');
    date_default_timezone_set('Asia/Kolkata');
    $edited_test = array();

    if (!empty($sID)) {
        foreach($sID as $k => $v) {
            $edited_test = array(
                'test_id' => $sID[$k],
                'test_priceUpdt' => $sAmt[$k],
                'fran_office_id' => $sOfficeId,
                'last_edit_date' => date('Y-m-d H:i:s', time())
            );

            $edited_test = json_encode($edited_test);
            $postData[] = array('test_id' => $v, 't_franchise_price' => $edited_test);
        }
        $data['franchise_tst_pkg'] = (object) $postData;
    }

    
    #-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - #
    if ($this - > form_validation - > run() === true) {

        $this - > franchise_price_model - > batchTestupdate($postData);

        $this - > session - > set_flashdata('message', display('save_successfully'));
        redirect('branch/franchise_price/create');


}

**My Model is **

public function batchTestupdate($data = [])
		{
			$this->db
				->update_batch($this->table_test, $data , 'test_id');
		}

View

<tr>
  <td>
    <input type="text" name="test_name[]" class="form-control" placeholder="" value="<?php echo $subject->test_name; ?>" disabled>
    <input type="hidden" name="test_id[]" class="form-control" placeholder="" value="<?php echo $subject->test_id; ?>">
  </td>
  <td>
    <input type="text" name="test_price[]" class="form-control" placeholder="" value="<?php echo $subject->test_price; ?>" disabled>
  </td>
  <td>
    <input type="text" name="test_priceUpdt[]" class="form-control" placeholder="" value="<?php echo $subject->test_price; ?>" id="test_priceEdt">
  </td>
</tr>

Appends on table field t_franchise_price rather than overwrite.

Change:

$this - > franchise_price_model - > batchTestupdate($postData);

To:

$this->franchise_price_model->batchTestupdate($postData, 2);

Change your model method to this:

public function batchTestupdate($data = [], $method=1){
    $db_table = $this->db->dbprefix($this->table_test);
    $sql = "";

    if($method == 1){
        $this->db->update_batch($this->table_test, $data , 'test_id');
    }
    else if($method == 2){
        foreach($data as $k=>$v){
            $sql = "UPDATE $db_table SET t_franchise_price = TRIM(BOTH ',' FROM CONCAT(COALESCE(t_franchise_price,''), ',', ?)) WHERE test_id = ?;";
            $result = $this->db->query($sql, array($v['t_franchise_price'], $v['test_id']));
            if($result === false) {
                echo "ERROR at index $k - query: ((".$this->db->last_query()."))<br/><br/>\n\n";
                print_r($this->db->error()); echo "<br/><br/>\n\n";
            }
        }
    }
}