ASP.NET发出Logon_User请求

Question

我只是创建了一个强大的变量来请求会话的logon_name。我这样做的原因是因为logon_name为我提供了例如daniel.ellison，而用户名变量给了我T12345（我们公司的员工ID）。如果我将@logon_name切换为@username并将我的DB的用户名值更改为我的员工ID，则可以正常工作。当我将数据库的用户名切换回daniel.ellison并将其切换回@logon_name时失败。知道为什么会这样吗？

<%@ import namespace="System.Data" %> 
<%@ import namespace="MySql.data.MySqlclient" %> 
<%@ import namespace="MySql.data.MySqlclient.MySqlConnection" %> 

    <Script runat="server"> 
        Sub page_load()
            Dim username As String = Convert.ToString(User.Identity.Name.Substring(User.Identity.Name.IndexOf("\") + 1))
            Dim logon_name As String = Request.ServerVariables("LOGON_USER")
            Dim dbconn As MySqlConnection
            Dim mySqlCommand As MySqlCommand
            Dim counter As Integer
            Dim isInGroup As Boolean
            Dim strSQL As String = "SELECT COUNT(*) FROM tbl_staff WHERE username = @logon_name AND group_id = 1001;"

            dbconn = New MySqlConnection("server=localhost;database=imc_directory_tool;user=Directory_Admin;port=3306;password=IMCisgreat2014;")
            dbconn.Open()

            mySqlCommand = New MySqlCommand(strSQL, dbconn)
            mySqlCommand.Parameters.AddWithValue("@logon_name", username)
            counter = mySqlCommand.ExecuteScalar()
            isInGroup = counter > 0
            If isInGroup = True Then
                Response.Write(logon_name)
                Response.Write("You are part of group_id 1001")
            Else
                Response.Write(logon_name)
                Response.Write("You are not part of group_id 1001")
            End If
            dbconn.Close()
        End Sub
    </Script>