Visual Basic 2010和Access数据库中的登录表单

Question

当我尝试登录我的系统时，我在包含以下内容的行上收到“COMexception未处理”错误：

  

DBConn.Open（“Provider = Microsoft.Jet.OLEDB.4.0;”

这是搜索数据库的函数的代码：

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;" & "DataSource = '" & Application.StartupPath & "\LoginDB.mdb'")
    User.Open("UserTable", DBConn, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockOptimistic)

    UserFound = False
    Login = False
    Username = "Username = '" & txtboxUsername.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 <> txtboxUsername.Text Then
                User.movenext()
            Else
                UserFound = True
                If PassDB = txtboxPassword.Text Then
                    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

End Function