狐爸，我设计的登录窗口，然后连接了sql数据库。当输入一个数据库里没有的姓名的时候，会提示以下错误，我想问下，该怎么修改呢？

此主题相关图片如下：未命名.jpg

登录界面的确定代码如下：

Dim UserName As String = e.Form.Controls("UserName").Value
Dim cmd As New SQLCommand
Dim dt As DataTable
Dim dr As DataRow
Dim i As Integer
cmd.C
If UserName = "" Then
    Messagebox.show("请选择用户!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
    Return
End If

cmd.CommandText = "Select * From {Users} Where [Name] = \'" & UserName & "\'"
dt = cmd.ExecuteReader
i = cmd.ExecuteScalar
dr = dt.DataRows(0)

If e.Form.Controls("PassWord").Value = dr("Password") Then
    _UserName = UserName
    _UserGroup = dr("Group")
    e.Form.Close
StatusBar.Message2 = "当前用户" &  _usergroup  & "-" &   _username & "☆"
Else
    Messagebox.show("密码错误!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
End If