对文件存取时必须按指针进行，效率较低，采用这种物理结构的是 。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='30162' and id < 2440402 and id<>'2440402' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30162' and id > 2440402 and id<>'2440402' order by id asc limit 5