login.vb

这是一个完善的图书馆管理系统.后台数据库采用ACCESS.

Public Class frmLogin
    Inherits System.Windows.Forms.Form

#Region " Windows 窗体设计器生成的代码 "

    Public Sub New()
        MyBase.New()

        '该调用是 Windows 窗体设计器所必需的。
        InitializeComponent()

        '在 InitializeComponent() 调用之后添加任何初始化

    End Sub

    '窗体重写 dispose 以清理组件列表。
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Windows 窗体设计器所必需的
    Private components As System.ComponentModel.IContainer

    '注意: 以下过程是 Windows 窗体设计器所必需的
    '可以使用 Windows 窗体设计器修改此过程。
    '不要使用代码编辑器修改它。
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents btnLogin As System.Windows.Forms.Button
    Friend WithEvents txtUserName As System.Windows.Forms.TextBox
    Friend WithEvents txtPassword As System.Windows.Forms.TextBox
    Friend WithEvents btnClose As System.Windows.Forms.Button
    Friend WithEvents btnOK As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Label1 = New System.Windows.Forms.Label
        Me.Label2 = New System.Windows.Forms.Label
        Me.Label3 = New System.Windows.Forms.Label
        Me.btnLogin = New System.Windows.Forms.Button
        Me.txtUserName = New System.Windows.Forms.TextBox
        Me.txtPassword = New System.Windows.Forms.TextBox
        Me.btnClose = New System.Windows.Forms.Button
        Me.btnOK = New System.Windows.Forms.Button
        Me.SuspendLayout()
        '
        'Label1
        '
        Me.Label1.Font = New System.Drawing.Font("宋体", 21.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(134, Byte))
        Me.Label1.ForeColor = System.Drawing.Color.FromArgb(CType(192, Byte), CType(0, Byte), CType(192, Byte))
        Me.Label1.Location = New System.Drawing.Point(16, 16)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(256, 32)
        Me.Label1.TabIndex = 0
        Me.Label1.Text = "图书管理系统V1.0"
        '
        'Label2
        '
        Me.Label2.Location = New System.Drawing.Point(40, 80)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(48, 23)
        Me.Label2.TabIndex = 0
        Me.Label2.Text = "用户名"
        '
        'Label3
        '
        Me.Label3.Location = New System.Drawing.Point(40, 112)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(48, 23)
        Me.Label3.TabIndex = 0
        Me.Label3.Text = "密码"
        '
        'btnLogin
        '
        Me.btnLogin.Location = New System.Drawing.Point(40, 152)
        Me.btnLogin.Name = "btnLogin"
        Me.btnLogin.Size = New System.Drawing.Size(48, 23)
        Me.btnLogin.TabIndex = 1
        Me.btnLogin.Text = "登录"
        '
        'txtUserName
        '
        Me.txtUserName.Location = New System.Drawing.Point(96, 80)
        Me.txtUserName.MaxLength = 20
        Me.txtUserName.Name = "txtUserName"
        Me.txtUserName.Size = New System.Drawing.Size(120, 21)
        Me.txtUserName.TabIndex = 2
        Me.txtUserName.Text = "admin"
        '
        'txtPassword
        '
        Me.txtPassword.Location = New System.Drawing.Point(96, 112)
        Me.txtPassword.MaxLength = 20
        Me.txtPassword.Name = "txtPassword"
        Me.txtPassword.PasswordChar = Microsoft.VisualBasic.ChrW(42)
        Me.txtPassword.Size = New System.Drawing.Size(120, 21)
        Me.txtPassword.TabIndex = 2
        Me.txtPassword.Text = "1111"
        '
        'btnClose
        '
        Me.btnClose.DialogResult = System.Windows.Forms.DialogResult.Cancel
        Me.btnClose.Location = New System.Drawing.Point(168, 152)
        Me.btnClose.Name = "btnClose"
        Me.btnClose.Size = New System.Drawing.Size(48, 23)
        Me.btnClose.TabIndex = 1
        Me.btnClose.Text = "关闭"
        '
        'btnOK
        '
        Me.btnOK.DialogResult = System.Windows.Forms.DialogResult.OK
        Me.btnOK.Location = New System.Drawing.Point(168, 152)
        Me.btnOK.Name = "btnOK"
        Me.btnOK.Size = New System.Drawing.Size(40, 23)
        Me.btnOK.TabIndex = 1
        '
        'frmLogin
        '
        Me.AcceptButton = Me.btnLogin
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.CancelButton = Me.btnClose
        Me.ClientSize = New System.Drawing.Size(282, 197)
        Me.Controls.Add(Me.txtUserName)
        Me.Controls.Add(Me.btnLogin)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.Label3)
        Me.Controls.Add(Me.txtPassword)
        Me.Controls.Add(Me.btnClose)
        Me.Controls.Add(Me.btnOK)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog
        Me.MaximizeBox = False
        Me.Name = "frmLogin"
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
        Me.Text = "系统登录"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Dim DataReader As System.Data.OleDb.OleDbDataReader

    Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Me.Close()
    End Sub

    Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
        Dim str As String
        Dim filename As String = Application.ExecutablePath()
        filename = filename.Substring(0, filename.LastIndexOf("\") + 1)
        filename = filename & "library.mdb"

        Try
            If OleConn.AccessConnection(filename, "", "") Then  '连接数据库成功
                str = "select logpwd from 管理员 where logname='" & txtUserName.Text & "'" '构造查询字串
                If OleConn.SelectQuery(str, DataReader) Then    '执行查询成功
                    If DataReader.HasRows Then  '如果找到
                        While DataReader.Read
                            If DataReader.Item(0) = txtPassword.Text Then   '如果密码正确
                                UserName = txtUserName.Text
                                Password = txtPassword.Text
                                btnOK.PerformClick()                        '回到主界面
                            Else                                            '密码不正确
                                MsgBox("密码不正确，请检查密码")
                            End If
                        End While
                    Else                    '没有找到记录
                        MsgBox("找不到此用户，请检查用户名")
                    End If
                Else        '执行查询失败
                    MsgBox("查询数据库失败")
                End If
            Else            '连接数据库失败
                MsgBox("连接数据库失败")
            End If
        Catch ex As Exception
            OleConn.DisplayError(ex)
        Finally
            DataReader.Close()
        End Try
    End Sub
End Class