#所有商品的類別 $sql = "select count(*) as count ,b.sn,b.ofsn,b.title from ".$xoopsDB->prefix($tbl_main)." as a left join ".$xoopsDB->prefix($tbl_kind)." as b on a.kind = b.sn {$andKey} group by a.`kind` order by b.ofsn,b.sort";//die($sql); ``` 只要「 group by a.`kind`」,商品檔的 類別 欄位,就可輕易的計算所有商品各類別的數量 4. 加總:sum(欄位)、平均:avg(欄位)