access登录窗口校验代码一

Private Sub login_Click()
If IsNull(Me.username) Then
MsgBox "请输入用户名！", vbExclamation
ElseIf IsNull(Me.password) Then
MsgBox "请输入密码！", vbExclamation
ElseIf key1 = DLookup("password", "user", "用户名 = '" & Me.username & "'") Then
DoCmd.OpenForm "登录界面" '打开登录界面
Else
MsgBox "密码不正确！", vbExclamation
End If
End Sub