????1.????????
????$sql1="insert into content(category??subject??content??username??release_date) values('{$category}'??'{ $subject}'??'{$content}'??'{$user}'??'{$date}')";
????//????????в???????????
????$res1=dml($sql1);
????2.???????
??????1??????????????????д????????
??????2???????????????????????var_dump($xxx)??????????????????????????
??????3???????????NULL??Σ????????desc table_name???????????????????? not null ????????????????????2????????????????????????????????