主题：BOM数据展开，制造业的高手请进！

多级反展和用途反展（顶层反展）的代码执行速度好艰难啊，大约2分钟，太慢了，另外这两个功能的代码为什么会报错呢，代码如下：
dim al as string=Forms("frm_b").Controls("TextBox1").value
'多级反展：
 Dim s As String =  " ;with cte As "  & _
    "(select * from abt00000 where childitem = '"  & al  & "'  "  & _
    "union all  "  & _
    "select a.* from abt00000 a  "  & _
    "join cte on a.childitem  = cte.parentitem) "  & _
    "select  * from cte "
    tables("frm_b_table1").Fill(s,"erp",true)

'用途反展：
Dim s As String =  " ;with cte As "  & _
    "(select * from abt00000 where childitem = '"  & al  & "'  "  & _
    "union all  "  & _
    "select a.* from abt00000 a  "  & _
    "join cte on a.childitem  = cte.parentitem) "  & _
    "select  * from cte left join abt00000 b on cte.parentitem = b.childitem where b.childitem is null"
    tables("frm_b_table1").Fill(s,"erp",true)