how to retrieve data from multiple table

You can use "join" in the CI query builder. Like this:

PHP Code:

$this->db
->select('t1.maincat_name,t2.subcat_name')
->from('categories t1')
->join('subcategories t2','t2.cat_id = t1.id')
->where('t1.maincat_name','Jokes');
$query = $this->db->get(); 


For more information:
http://www.codeigniter.com/userguide3/da...lder::join