weix_id=request.form("weix_id")

sql="select * from weix where weix_id="&weix_id

用这个试试：
dim weix_id
weix_id=""&trim(request("weix_id"))
if weix_id<>"" then
sql="select * from weix where weix_id="&weix_id
.......
response.write(weix_id)
else
response.write("weix_id的值没传过来！")
end if