Postgresql error in try block

Sorry, if my way was wrong, what is the right way?
I hope I explained what I want clear?

Code:

       $func_name = 'pd_update_settings_no_exists';
       $query = $this->db->query("select exists(select * from pg_proc where proname = '".$func_name."')");
       if(!$query->row()->exists){
           echo "Func not found!";
       }