How to check if id already exists - codeigniter

Model

<?php
class Fruits_model extends CI_Model
{
    function __construct()
    {
        parent::__construct();
        $this->load->database();
    }

    function check()
    {
        $query = null; //emptying in case 

        $id   = $_POST['id']; //getting from post value
        $name = $_POST['name'];

        $query = $this->db->get_where('fruits', array(//making selection
            'id' => $id
        ));

        $count = $query->num_rows(); //counting result from query

        if ($count === 0) {
            $data = array(
                'name' => $name,
                'id' => $id
            );
            $this->db->insert('fruits', $data);
        }
    }
}

?>

$ql = $this->db->select('id')->from('testing')->where('id',$id)->get();

if( $ql->num_rows() > 0 ) {} else {
    $a = array('id' => $id, 'message' => $message);
    $this->db->insert('testing', $a);
}

This should do it.

You have a logic issue with your code that you need to fix.

In your code, you save the result from your query as $q = $this->db->get('testing'), and $q will always evaluate to true regardless of the number of rows your return.

You need to check the number of rows using $query->num_rows() > 0 and then the rest of you code will behave as you expect.

For more details, see: http://ellislab.com/codeigniter/user-guide/database/results.html