Update query throws error in mysql

I have a table named "mostread" with 2 columns open_id (int) and read (int). Now the problem is that the "open_id" is already present in the table, then I need to update the "read" for every mouse click, I need to insert a new line with the "open_id" fetched from the controller and read = 1. I am using the below code in my model that inserts a new row correctly, but the second time I click on it, an error is thrown as follows.

Database error has occurred

Error #: 1064 You have an error in your SQL syntax; check the manual corresponding to your MySQL server version for the correct syntax to use next to 'read = read + 1 WHERE open_id

=' 193 '' on line 1

UPDATE mostread

SET read = read + 1 WHERE open_id

= '193'

File name: D: /Xampp/htdocs/opunletter/opunletter/application/models/Select.php

Line number: 52

             public function click($id)  
      {  
           $query = $this->db->query("SELECT * FROM mostread WHERE open_id='$id'");  

$count= $query->num_rows();
    if($count > 0) {
        $this->db->set('read', 'read+1', FALSE);
        $this->db->where('open_id', $id);
        $this->db->update('mostread');

        $data = array( 
   'open_id' => $id,
   'read' => '1'
);

$this->db->insert('mostread', $data); 
          return TRUE;
    }else{
         return FALSE;
     }
      }