如何添加Select Distinct？

Question

This query search for products, there are products that has the same name but not the same size or whatever.

How can I add Select Distinct on this code?

private function query_products($category = 1, $id = NULL, $search = NULL){  
    $this->db->select('PP.*');  
    $query= $this->db->from("PLUGIN_PRODUCTS PP");  

    //->where('PCP.COUNTRY', $country);  


    if($search == NULL):  
    $query = $query->where('PP.PRODUCT_CATEGORY', $category);  

    else:

    $query = $query->like('PP.PRODUCT_NAME', $search)  
            ->or_like('PP.PRODUCT_DESCRIPTION', $search)  
            ->or_like('PP.PRODUCT_CODE', $search)  
            ->group_by("PP.ID");
    endif;  

    if(!empty($id)):  
    $query = $query->where('PP.ID', $id);  
    endif;  

    return $query;  
  }  

Answer 1

change this

   ->group_by("PP.ID");

to

  ->group_by("PP.PRODUCT_NAME , PP.PRODUCT_SIZE");