这个sql语句怎么运行不了。

<!--#include file="conn.asp"-->
<%
    Set rs = server.CreateObject("adodb.recordset")
    sql = "select * from b "
    rs.Open sql, conn, 1, 3
    do while not rs.eof
    zhuye=rs("zhuye")
    dianhua=rs("dh")
    Set rs1 = server.CreateObject("adodb.recordset")
    sql1="select * from a where dh='"&rs("dh") and zhuye="" &"'"
    rs1.Open sql1, conn, 1, 3
    do while not rs1.eof
    rs1("zhuye") = zhuye
    rs1.update
    rs1.movenext
loop
rs1.close
    rs.movenext
loop
rs.close
set rs=nothing

response.write "更新完毕"  
   
    %>


原先这句是可以正常运行的：sql1="select * from a where dh='"&rs("dh") &"'"

后面加个判断语句，要是 zhuye字段为空，才更新 : sql1="select * from a where dh='"&rs("dh") and zhuye="" &"'"

但是这个语句有问题：Microsoft VBScript 运行时错误 (0x800A000D)
类型不匹配: '[string: "select * from a wher"]'
/albb/albb.asp, 第 10 行


到底该怎么写呢。。。。。请教下大家


先~谢谢~了~~