MySQL server error report:Array ( [0] => Array ( [message] => MySQL Query Error ) [1] => Array ( [sql] => SELECT g.goods_id,goods_name,shop_price,goods_thumb,cat_id,url_name,url_name as url_defined,brand_id,supplier_id,g.goods_sn,g.market_price0 as market_price , RAND() AS rnd FROM `mayitao`.`yp_goods_recommend` as gr left join `mayitao`.`yp_items` AS g on g.goods_id = gr.goods_id WHERE gr.is_new=1 and g.cat_id > 0 order by sort_order asc limit 9 ) [2] => Array ( [error] => Column 'sort_order' in order clause is ambiguous ) [3] => Array ( [errno] => 1052 ) )