news category and subcategory

the below code gives error

Code:

Error Number: 1052

Column 'cat_id' in where clause is ambiguous

SELECT * FROM (`news`) JOIN `cat` ON `news`.`cat_id` = `cat`.`cat_id` WHERE `cat_id` = '1' OR `parent_id` = '1'

Filename: C:\wamp\www\toyda\system\database\DB_driver.php

Line Number: 330

PHP Code:

$query = $this->db->from("news")
                ->join("cat", "news.cat_id = cat.cat_id")
                ->where("cat_id", "1")
                ->or_where("parent_id", "1")
                ->get();      
  return $query->result();