你的sql语句有问题

select ID,Tid,Title,Picurl from KS_Article where tid in({$CurrClassChildID}) and KeyWords=(select KeyWords from KS_Article where id='{$CurrInfoID}') order by id desc

不能加单引号,因为id是数字型的

正确的应该是

select ID,Tid,Title,Picurl from KS_Article where tid in({$CurrClassChildID}) and KeyWords=(select KeyWords from KS_Article where id={$CurrInfoID}) order by id desc