中国农业科学 小木虫:有一段查询的ASP代码，请高手解释下。

<%
getcondition = replace(trim(request("condition")),"'","''")
getkey = replace(trim(request("key")),"'","''")
If(Session("StuID") = "")Then
Response.Redirect("Index.asp")
Response.End()
End If
if(getcondition = "" or getkey = "")then
rssql = "Select * from tb_StuResult where stu_id='"&session("StuID")&"' order by res_subdate Desc"
else
If(InStr(getcondition,"res_subdate") > 0)Then
If(InStr(getkey,"-") > 0)Then
darray = Split(getkey,"-")
getkey = ""
For a=0 To Ubound(darray)
If(len(darray(a)) = 1 )Then
darray(a) = "0"&darray(a)
End If
getkey = getkey&darray(a)&"-"
Next
getkey = Mid(getkey,1,len(getkey)-1)
End If
rssql = "select * from tb_StuResult where convert(varchar(10),"&getcondition&",121) like '%"&getkey&"%' and stu_id='"&session("StuID")&"' order by res_subdate Desc"
Else
rssql = "Select * from tb_StuResult where "&getcondition&" like '%"&getkey&"%' and stu_id='"&session("StuID")&"' order by res_subdate desc"
End If
end if