dim conn as oledbconnection
conn=new oledbconnection() '建立一个oledbconnection对象
conn.connectionstring="provider=microsoft.jet.oledb.4.0;" & _
"data source=" & server.mappath("db/dissuss.mdb") '设置连接字符串connectionstring
conn.open()
dim cmd as oledbcommand
'建立command对象，并且指定SQL语句
dim strsql as string
strsql="select max(id) from content"
cmd =new oledbcommand(strsql,conn)
dim rd as oledbdatareader '声明一个DATAREADER对象
dim maxid as integer ‘记录当前最大记录数
rd=cmd.executereader '执行SQL指令，炳将其结果设置给datareader
if not isdbnull(rd.read()) then
maxid=rd.item("id")+1
else
maxid=1
end if


错误的是 maxid=rd.item("id")+1 这一行 谁能告诉我什么原因呀