with ts as (

  select fitemclassid,fitemid,fnumber,Fparentid,fname,FFullNumber from t_item where  Fparentid=0 and fitemclassid=4

    --首先要查询出最原始父级的信息

  union all

    --全连接

  select a.fitemclassid,a.fitemid, a.fnumber,a.Fparentid,a.fname,a.FFullNumber from t_item a inner join ts b on a.Fparentid=b.fitemid

    --将整体的查询结果重新嵌套进语句中，将查询结果集中子类的ID与父类ID关联，进行查询

  )

  select * from ts  order by fnumber