釆用分层随机抽样要注意的原则是

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='30773' and id < 2477761 and id<>'2477761' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30773' and id > 2477761 and id<>'2477761' order by id asc limit 5