1 用户登录代码（frmLogin.vb）
Public Class frmLogin
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
If usename.Text = " " And password.Text = " " Then
Me.Hide()
frmMain.Show()
Else
MsgBox("用户名或者密码错误")
End If
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button2.Click
Me.Close()
End Sub
End Class
2 主界面代码（frmMain.vb）
Public Class frmMain
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
Me.Hide()
frmAddData.Show()
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button3.Click
Me.Hide()
frmViewData.Show()
End Sub
