下面是我的代码,看一下哪儿有问题:

dim str as string
Dim hname As String = Request.QueryString(usname.Text)
Dim strs As String = "select * from users where username='" & hname & "'"
Dim cmd2 As New OleDbCommand(strs, conn)
conn.Open()
Dim dr As OleDbDataReader = cmd2.ExecuteReader()
If dr.Read() = True Then
message.Text = "此用户已经存在!"
Else
str = "insert into users(username,userpwd,realname,) values('" & usname.Text & "','" & uspwd.Text & "','" & realname.Text & "')"
Dim cmd As New OleDbCommand(str, conn)
cmd.ExecuteNonQuery() '提示这行有错
conn.Close()
message.Text = "注册成功!"
End If

提示错误:已有打开的与此连接相关联的 DataReader，必须首先将它关闭。

我整个页面就只有这一个conn.open()啊,怎么会出这个错误呢???

private void Button1_Click(object sender, System.EventArgs e)
{
string str="select Admin_ID,Admin_psw from p_AdminInfo where Admin_name='"+TextBox1.Text+"'";
SqlConnection con = new SqlConnection("server=127.0.0.1;uid=sa;database=pubs;");
con.Open();
SqlCommand com=new SqlCommand(str,con);
SqlDataReader dr=com.ExecuteReader();
try
{
if(dr.Read())
{
if(dr.GetString(1)==TextBox2.Text)
{
Session["Admin_ID"]=dr["Admin_ID"].ToString();
Response.Redirect("adminIndex.aspx");
}
else
{
Response.Write("用户密码不正确!");
}
}
else
{
Response.Write("无此用户 !");
}
}
finally
{
dr.Close();
con.Close();
con.Dispose();
}
}
}

cmd.ExecuteNonQuery()
cmd.Close()
conn.Close()
把CMD关了啊

谢谢两位了,我试一下~~

你还可以使用arjx来实现无刷新判断用户名是否存在，这样的效果可能比较好一点呀！！！

“arjx”是什么？
应该是AJAX （Asynchronous JavaScript and XML）的缩写

我靠，你别逗了！·！这都不知道，你是怎么学习ASP.NET的！！你可以到Arjx论坛去看看，那里有好都这样的例子！！