在Access VBA

Question

我目前正在使用以下代码为我的用户提供Microsoft Access中的登录表单。它最初设计为接受UserID列中的用户名ID，该列是表Employees Table内的自动编号列。

代码工作正常，但我不想再使用用户ID，而是使用我创建的名为Username的列链接到组合框cbo_Employee以验证使用密码的正确用户名。

我认为该值目前存储在lngMyUsername中，但它只会存储数字，如果我尝试将其设置为string，我会在行{{1}上找到数据类型不匹配}

附上一些图片，概述了我的If Me.txt_Password.Value <> DLookup("Password", "Employees Table", "[Username]=" & lngMyUsername) Then和Employees Table数据属性的结构。

任何帮助将不胜感激。如果您需要更多信息，请不要犹豫。

谢谢， 贾尔斯。

cbo_Employees

编辑：下面是修改后的代码，正常工作时会再次更新。

Private Sub cmdLogin_Click()
        'Check to see if data is entered into the Username combo box
    Dim lngMyUsername As Long
    If IsNull(Me.cbo_Employee) Or Me.cbo_Employee = "" Then
        MsgBox "You Must enter a Username.", vbOKOnly, "Required Data"
        Me.cbo_Employee.SetFocus
        Exit Sub
    End If
    lngMyUsername = Me.cbo_Employee.Value

    'Check to see if data is entered into the password box

If IsNull(Me.txt_Password) Or Me.txt_Password = "" Then
    MsgBox "You must enter a Password.", vbOKOnly, "Required Data"
    Me.txt_Password.SetFocus
    Exit Sub
End If

'Check value of password in Employees Table to see if this matches value chosen in combo box
If Me.txt_Password.Value <> DLookup("Password", "Employees Table", "[Username]=" & lngMyUsername) Then
    MsgBox "Password Invalid. Please Try Again", vbOKOnly, "Invalid Entry!"
    Me.txt_Password.SetFocus
    Me.txt_Password = Null
    intLogonAttempts = intLogonAttempts + 1
    'If user enters incorrect password 3 times database will shutdown
    If intLogonAttempts >= 3 Then
        MsgBox "You do not  have access to this database. Please contact your system administrator.", vbCritical, "Restricted Access!"
        Application.Quit
    End If

Else
    Me.txt_Password = Null
    'Open correct form
    Dim strAccessLevel As String

    strAccessLevel = DLookup("Admins", "Employees Table", "Username=" & lngMyUsername)

    If strAccessLevel = "Admin" Then
        MsgBox "Welcome " & DLookup("EmployeeName", "Employees Table", "Username=" & lngMyUsername)
        DoCmd.Close
        DoCmd.OpenForm "A"
    ElseIf strAccessLevel = "Manager" Then
        MsgBox "Welcome " & DLookup("EmployeeName", "Employees Table", "Username=" & lngMyUsername)
        DoCmd.Close
        DoCmd.OpenForm "B"
    ElseIf strAccessLevel = "User" Then
        MsgBox "Welcome " & DLookup("EmployeeName", "Employees Table", "Username=" & lngMyUsername)
        DoCmd.Close
        DoCmd.OpenForm "C"
    End If
End If

End Sub

Answer 1

修改 所以你已经改变了代码，使用Username而不是UserID。这清除了事情。

在这种情况下，请使用字符串变量strMyUsername，对于密码检查，您需要将参数括在'...'中：

' Just to be safe: unmasked ' would break the query
strMyUsername = Replace(strMyUsername, "'", "''")

If Me.txt_Password.Value <> DLookup("Password", "Employees Table", _
    "[Username] = '" & strMyUsername & "'") Then
        ' wrong password...

修改2

此行应该有效

strAccessLevel = DLookup("Admins", "Employees Table", "[Username] = '" & strMyUsername & "'")

但当然还没有：

MsgBox "Welcome " & DLookup("EmployeeName", "Employees Table", "Username=" & strMyUsername)

但是，由于您正在阅读“员工表”中的多个字段，因此我建议采用不同的方法：将所有字段一次性读入记录集。
然后，您可以按DLookup

替换所有RS!Field次来电

OpenRecordset在检查用户名和密码设置后属于。

Dim RS As Recordset
Set RS = CurrentDb.OpenRecordset("SELECT * FROM [Employees Table] WHERE [Username] = '" & strMyUsername & "'", dbOpenSnapshot)

If Me.txt_Password.Value <> Nz(RS!Password) Then
' ...
strAccessLevel = RS!Admins
' ...
MsgBox "Welcome " & RS!EmployeeName

编辑3

见Debugging VBA。

在Set RS = CurrentDb.OpenRecordset行设置断点 将鼠标悬停在strMyUsername上 - 它是否包含您期望的值？
执行该行。
在立即窗口（Ctrl + G）中：? RS.EOF如果EOF为true，则没有记录。

? RS.Name为您提供SQL。复制它，从中创建一个新查询，然后运行它。这将有助于弄清楚为什么它没有得到记录。