帮我看看，那里错了，最好能给讲解一下

<%
Response.Expires=0
Function f_Bin2Str(ByVal sBin)
Dim iI, iLen, iChr, iRe
iRe = ""
If Not IsNull(sBin) Then
iLen = LenB(sBin)
For iI = 1 To iLen
iChr = MidB(sBin, iI, 1)
If AscB(iChr) > 127 Then
iRe = iRe & Chr(AscW(MidB(sBin, iI + 1, 1) & iChr))
iI = iI + 1
Else
iRe = iRe & Chr(AscB(iChr))
End If
Next
End If
f_Bin2Str = iRe
End Function
iConcStr = "Provider=Microsoft.Jet.OLEDB.4.0;Persist Security Info=False" & _
";Data Source=" & server.mappath("zj.mdb")
iSql="tb_img"
set iRe=Server.CreateObject("ADODB.Recordset")
iRe.Open iSql,iConcStr,1,3
iLen=Request.TotalBytes
sBin=Request.BinaryRead(iLen)
iCrlf1 = ChrB(13) & ChrB(10)
iCrlf2 = iCrlf1 & iCrlf1
iLen = InStrB(1, sBin, iCrlf1) - 1
iSpc = LeftB(sBin, iLen)
sBin = MidB(sBin, iLen + 34)
iPos1 = InStrB(sBin, iCrlf2) - 1
While iPos1 > 0
iStr = f_Bin2Str(LeftB(sBin, iPos1))
iPos1 = iPos1 + 5
iPos2 = InStrB(iPos1, sBin, iSpc)

iPos3 = InStr(iStr, "; filename=""") + 12
If iPos3 > 12 Then
iStr = Mid(iStr, iPos3)
iPos3 = InStr(iStr, Chr(13) & Chr(10) & "Content-Type: ") - 2
iFn = Left(iStr, iPos3)
If iFn <> "" Then
iRe.AddNew
ire("path")=left(iFn,instrrev(iFn,"\"))
iRe("fname") = mid(iFn,instrrev(iFn,"\")+1)
iRe("type") = Mid(iStr, iPos3 + 18)
iRe("img").AppendChunk MidB(sBin, iPos1, iPos2 - iPos1)
iRe.Update
End If
End If

sBin = MidB(sBin, iPos2 + iLen + 34)
iPos1 = InStrB(sBin, iCrlf2) - 1
Wend
iRe.close
set iRe=Nothing
%>