有三个关系R、S和T如下:则由关系R和S得到关系T的操作是( )

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SQL Error: select id,body,options from ***_enewstiku where sourceid='29842' and id < 2421975 and id<>'2421975' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29842' and id > 2421975 and id<>'2421975' order by id asc limit 5