机房收费系统总结(登陆界面)

        机房收费系统完事了,但是学习的总结和积累才刚刚开始,做系统我们要积累经验,整个系统有很多的思想我们不论到什么时候都是需要用到的,这些都是我们总结积累下来的. 登陆界面.整个过程分这么几个层次

          验证是否为空

          验证是否超过了限制的登陆次数

          验证用户名是否存在

          验证密码是否正确 代码演示如下

Private Sub cmdOK_Click()    Dim intCounts As Integer '用于保存用户请求验证次数    Dim ObjRst As Recordset    Dim StrSQL As String        '判断输入框是否为空    If Trim(txtUserID.Text) = "" Then        MsgBox "请输入用户名", vbOKOnly + vbExclamation, "提示"        txtUserID.SetFocus        Exit Sub    End If        If Trim(txtPWD.Text) = "" Then        MsgBox "请输入密码", vbOKOnly + vbExclamation, "提示"        txtPWD.SetFocus        Exit Sub    End If        intCounts = intCounts + 1 '计算登录次数            If intCounts > MaxLoginTimes Then '验证是否登陆次数超过限制        MsgBox "登陆次数超过限制！", vbCritical, "警告"        End    Else        '检查是否存在指定用户        StrSQL = "select * from User_Info where User_ID = '" & txtUserID.Text & "'"               Set ObjRst = ExecuteSQL(StrSQL)                If ObjRst.EOF Then            MsgBox "用户名错误！", vbOKOnly + vbCritical, "警告"            txtUserID.SetFocus            txtUserID.SelStart = 0            txtUserID.SelLength = Len(txtName.Text)            Exit Sub        Else            '检查密码是否正确            If Trim(ObjRst.Fields(3)) <> Trim(txtPWD.Text) Then                MsgBox "密码输入错误！", vbOKOnly + vbCritical, "警告"                txtUserID.SetFocus                txtUserID.SelStart = 0                txtUserID.SelLength = Len(txtPW.Text)                Exit Sub                            Else                                Unload Me '卸载登录窗体                frmMain.Show            End If                      End If    End IfEnd Sub当然这只是最最简单的登陆界面还可以加入字符限制比如限制只能输入数字和英文字符如下

Public Function Check(ByVal Str2 As String) As Boolean     Dim i As Integer       Check = False            For i = 0 To Len(Str2) - 1        str1 = Mid(Str2, i + 1, 1)        If (Asc(str1) >= 45 And Asc(str1) <= 57) Or (Asc(str1) >= 65 And Asc(str1) <= 90) Or (Asc(str1) >= 97 And Asc(str1) <= 122) Or (Asc(str1) = 8) Or (Asc(str1) = 13) Then            Check = False        Else            Check = True            Exit Function        End If    Next iEnd Function

 慢慢积累才是王道