PDO数据库的一些操作记录

public function getbuy($uid,$persentProductID){

    return $this->db->from('policy_order')

        ->where('user_id',$uid)

//等同于 where 'user_id' = $uid

        ->where('product_main_id',$persentProductID)  

//$perentProductID为数组类型时，yuwhere 'product_main_id' in (  )

        ->orderBy('end_date desc')

//orderby end_date    [desc写在引号里]

        ->limit(1)

//limit 1

        ->fetch();