作业在系统中存在与否的惟一标志是 。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='30252' and id < 2447362 and id<>'2447362' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30252' and id > 2447362 and id<>'2447362' order by id asc limit 5