将3张桌子和PHP连接起来

最初,我有两个表Item和ItemFavorite。当我想要收藏的物品时,我会这样选择:

 @Query("SELECT prd.* FROM Item prd, ItemFavourite fp WHERE prd.id = fp.itemId order by fp.sorting ")

    function get_item_favourite( $conds = array(), $limit = false, $offset = false  )
{
    $this->db->select('bs_items.*'); 
    $this->db->from('bs_items');
    $this->db->join('bs_favourite', 'bs_favourite.item_id = bs_items.id');
    

    if(isset($conds['user_id'])) {

        if ($conds['user_id'] != "" || $conds['user_id'] != 0) {
                
                $this->db->where( 'user_id', $conds['user_id'] );   

        }

    }

    if ( $limit ) {
    // if there is limit, set the limit
        
        $this->db->limit($limit);
    }
    
    if ( $offset ) {
    // if there is offset, set the offset,
        $this->db->offset($offset);
    }
    
    return $this->db->get();
    // print_r($this->db->last_query());die;
    
}

我这样试过:

 @Query("select * from ItemFavourite fp left join Item prd on fp.itemId = prd.id left join ItemMoto im on fp.itemId = im.id")
LiveData<List<Item>> getAllFavouriteProducts();

和php:

    function get_item_favourite( $conds = array(), $limit = false, $offset = false  )
{
    $this->db->select('*'); 
    $this->db->from('bs_favourite');
    $this->db->join('bs_items', 'bs_items.id = bs_favourite.item_id');
    $this->db->join('bs_items_moto', 'bs_items_moto.id = bs_favourite.item_id', left);

    if(isset($conds['user_id'])) {

        if ($conds['user_id'] != "" || $conds['user_id'] != 0) {
                
                $this->db->where( 'user_id', $conds['user_id'] );   

        }

    }

    if ( $limit ) {
    // if there is limit, set the limit
        
        $this->db->limit($limit);
    }
    
    if ( $offset ) {
    // if there is offset, set the offset,
        $this->db->offset($offset);
    }
    
    return $this->db->get();
    // print_r($this->db->last_query());die;
    
}

我有两个最喜欢的项目和一个项目。当请求最喜爱的活动时,仅显示两个,即重复项MOTO。