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我使用 VB.NET 和 microsoft access 作为我的数据库，我是 VB.NET 的新手，我尝试根据当前角色设置不同的访问级别。例如，登录后，管理员将进入主页如果用户登录后，他们将被定向到不同的页面。我已经在我的数据库中设置了不同的角色，我在网上找到了一些编码来帮助我

但是我不断收到错误“未声明用户角色”。由于其保护级别，它可能无法访问。我需要先声明 UserRole 吗？如果是这样，我该怎么做？任何帮助将不胜感激，谢谢:)

Public Class Form1 Dim loginerror As String Dim UserRole As String Public Function login() Dim DBconn As New ADODB.Connection Dim user As New ADODB.Recordset

    Dim Username As String
    Dim userDB As String
    Dim passDB As String

    Dim UserFound As Boolean

    DBconn.Open("Provider = Microsoft.Jet.OLEDB.4.0;" & _
                "Data Source = '" & Application.StartupPath & "\LoginDB.mdb'")

    user.Open("UserTable", DBconn, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockOptimistic)

    UserFound = False
    login = False
    Username = "Username = '" & txtuser.Text & "'" '

    Do
        user.Find(Username)
        If user.BOF = False And user.EOF = False Then
            userDB = user.Fields("Username").Value.ToString

            passDB = user.Fields("Password").Value.ToString

            If userDB <> txtuser.Text Then
                user.MoveNext()
            Else
                UserFound = True
                If passDB = txtpass.Text Then
                    UserRole = user.Fields("roles").Value.ToString
                    user.Close()
                    DBconn.Close()
                    Return True
                Else
                    loginerror = "Invalid Password"
                    user.Close()
                    DBconn.Close()
                    Return False
                End If
            End If
        Else
            loginerror = "Invalid Username"
            user.Close()
            DBconn.Close()
            Return False
        End If
    Loop Until UserFound = True
    user.Close()
    DBconn.Close()
    Return False


End Function

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    If login() = True And UserRole = "admin" Then
        adminwelcome.Show()
        Me.Close()
    ElseIf login() = True Then
        Welcome.Show()
        Me.Close()
    Else
        MessageBox.Show(loginerror, "Login Message")
    End If
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    AcceptButton = Button1
    Me.Show()
    Application.DoEvents()
    txtuser.Focus()
End Sub

Private Sub txtpass_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtpass.TextChanged

End Sub

Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click

End Sub

Private Sub txtuser_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtuser.TextChanged

End Sub

Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click

End Sub

Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click

End Sub

Private Sub Label3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label3.Click

End Sub

结束类

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1 回答 1

0

我假设你正在拉用户角色从数据库中您收到此错误是因为尚未声明该变量。

我会提取该信息（用户的角色）并将其存储到名为UserRole的类级变量中。然后，您将能够在 Button1_Click 子中访问它。

Public Class Form1
Dim loginerror As String
Dim UserRole As String
Public Function login()
Dim DBconn As New ADODB.Connection
Dim user As New ADODB.Recordset

Dim Username As String
Dim userDB As String
Dim passDB As String

Dim UserFound As Boolean

DBconn.Open("Provider = Microsoft.Jet.OLEDB.4.0;" & _
            "Data Source = '" & Application.StartupPath & "\LoginDB.mdb'")

user.Open("UserTable", DBconn, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockOptimistic)

UserFound = False
login = False
Username = "Username = '" & txtuser.Text & "'" '

Do
    user.Find(Username)
    If user.BOF = False And user.EOF = False Then
        userDB = user.Fields("Username").Value.ToString

        passDB = user.Fields("Password").Value.ToString

        If userDB <> txtuser.Text Then
            user.MoveNext()
        Else
            UserFound = True
            If passDB = txtpass.Text Then
                UserRole = user.Fields("UserRole").Value.ToString
                user.Close()
                DBconn.Close()
                Return True
            Else
                loginerror = "Invalid Password"
                user.Close()
                DBconn.Close()
                Return False
            End If
        End If
    Else
        loginerror = "Invalid Username"
        user.Close()
        DBconn.Close()
        Return False
    End If
Loop Until UserFound = True
user.Close()
DBconn.Close()
Return False


End Function

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)             Handles Button1.Click

If login() = True And UserRole = "admin" Then
    adminwelcome.Show()
    Me.Close()
ElseIf login() = True Then
    Welcome.Show()
    Me.Close()
Else
    MessageBox.Show(loginerror, "Login Message")
End If
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
AcceptButton = Button1
Me.Show()
Application.DoEvents()
txtuser.Focus()
End Sub

Private Sub txtpass_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtpass.TextChanged

End Sub

Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click

End Sub

Private Sub txtuser_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtuser.TextChanged

End Sub

Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click

End Sub

Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click

End Sub

Private Sub Label3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label3.Click

End Sub

End Class
于 2013-07-16T02:04:33.077 回答