自学.net一年，第一个自己写的用户登录控件
事件CheckedResult，该事件参数e继承自EventArgs，含有用户名，密码，登录合法性(布尔值)
事件EnterEmpty，当用户名、密码文体框为空值时引发
Imports System.ComponentModel
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Data.SqlClient
")> Public Class Login
    Inherits System.Web.UI.WebControls.WebControl
    Implements IPostBackDataHandler
    Public Delegate Sub CheckedEvent(ByVal sender As Object, ByVal e As LoginEvent)
    Public Event EnterEmpty As EventHandler
    Public Event CheckedResult As CheckedEvent
    Private _user As String
    Private _pass As String
    Private _dataBase As String
    Private _dataTable As String
    Private _dataBaseUserName As String
    Private _dataBasePass As String
    Private _server As String
    Private _colUser As String
    Private _colPass As String
    Private _txtUser As String
    Private _txtPass As String
    Public Property ColUser() As String        属性--用户名字段
        Get
            Return _colUser
        End Get
        Set(ByVal value As String)
            _colUser = value
        End Set
    End Property
    Public Property ColPass() As String        属性--密码字段
        Get
            Return _colPass
        End Get
        Set(ByVal value As String)
            _colPass = value
        End Set
    End Property
    Public Property Server() As String        属性--SQL服务器名
        Get
            Return _server
        End Get
        Set(ByVal value As String)
            _server = value
        End Set
    End Property
    Public Property DataBaseUserName() As String        属性--数据库登录用户
        Get
            Return _dataBaseUserName
        End Get
        Set(ByVal value As String)
            _dataBaseUserName = value
        End Set
    End Property
    Public Property DataBasePass() As String        属性--数据库登录密码
        Get
            Return _dataBasePass
        End Get
        Set(ByVal value As String)
            _dataBasePass = value
        End