Question

您好我正在尝试在本地.mdf数据库中查看有关课程的详细信息，但似乎无法这样做，我已经有几个星期这个问题了，真的需要解决它所以任何帮助将不胜感激。我将在下面的表单中包含我的代码。在此先感谢您的帮助!!

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    Dim Session As String
    Session = txtSession.text

    Dim con As New SqlConnection
    Dim inscmd As New SqlCommand
    con.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings("RoomBookingSystem.My.MySettings.Database1ConnectionString1").ConnectionString
    Try
        Using cn As New SqlConnection(con.ConnectionString)
            con.Open()

            Dim ParamInitial As New SqlParameter
            ParamInitial.ParameterName = ("@StaffInitials")
            ParamInitial.Value = lblStaffInitials.Text.Trim()
            inscmd.Parameters.Add(ParamInitial)

            Dim ParamWeek As New SqlParameter
            ParamWeek.ParameterName = ("@Week")
            ParamWeek.Value = lblWeek.Text.Trim
            inscmd.Parameters.Add(ParamWeek)

            Dim ParamPeriod As New SqlParameter
            ParamPeriod.ParameterName = ("@Period")
            ParamPeriod.Value = lblPeriod.Text.Trim
            inscmd.Parameters.Add(ParamPeriod)

            Dim ParamDay As New SqlParameter
            ParamDay.ParameterName = ("@Day")
            ParamDay.Value = lblDay.Text.Trim
            inscmd.Parameters.Add(ParamDay)

            Dim ParamSubject As New SqlParameter
            ParamSubject.ParameterName = ("@Subject")
            ParamSubject.Value = lblSubject.Text.Trim
            inscmd.Parameters.Add(ParamSubject)

            Dim ParamYearGroup As New SqlParameter
            ParamYearGroup.ParameterName = ("@YearGroup")
            ParamYearGroup.Value = lblYear.Text.Trim
            inscmd.Parameters.Add(ParamYearGroup)

            Dim ParamNumberPupils As New SqlParameter
            ParamNumberPupils.ParameterName = ("@NumberOfPupils")
            ParamNumberPupils.Value = lblNoOfPupils.Text.Trim
            inscmd.Parameters.Add(ParamNumberPupils)

            Dim ParamControlledAssesment As New SqlParameter
            ParamControlledAssesment.ParameterName = ("@ControlledAssesment")
            ParamControlledAssesment.Value = lblControlledAssesment.Text.Trim
            inscmd.Parameters.Add(ParamControlledAssesment)

            Dim ParamRoom As New SqlParameter
            ParamRoom.ParameterName = ("@Room")
            ParamRoom.Value = lblRoom.Text.Trim
            inscmd.Parameters.Add(ParamRoom)

            Dim ParamSession As New SqlParameter
            ParamSession.ParameterName = ("@Session")
            ParamSession.Value = txtSession.Text.Trim
            inscmd.Parameters.Add(ParamSession)

            inscmd.CommandText = "INSERT INTO Booking (Week, Day, Period, Subject, YearGroup, StaffInitials, NumberOfPupils, Session, Room, ControlledAssesment)VALUES (@Week,@Day,@Period,@Subject,@YearGroup,@StaffInitials,@NumberOfPupils,@Session,@Room,@ControlledAssesment)"
            'inscmd.CommandText = "INSERT INTO Booking (Week, Day, Period, Subject, YearGroup, StaffInitials, NumberOfPupils, Session, Room, ControlledAssesment)VALUES ('B','Monday',5,'Politics','U6','JAGG',5,'5','LIT','False')"
            Print(inscmd.CommandText)
            inscmd.Connection = con
            inscmd.ExecuteNonQuery()
            con.Close()
            inscmd.Parameters.Clear()
        End Using
        ' Catch ex As Exception
        '   MsgBox("" & ex.Message)
        'if there is an error it will go here (can use Msgbox or label)
    Finally
        con.Close()
    End Try
    MsgBox("Your Booking Has Been Made Successfully")
    Clicky = False
    MainViewForm.btnBackToBooking.Visible = False
    FormView.Show()
    Me.Hide()
    con.Close()
End Sub

Answer 1

我在上面的示例中看到两个insert命令。注释掉的命令显示两个值被视为数字而不是字符串您使用使用参数的命令文本，但所有准备好的参数都设置为字符串数据类型（您没有设置任何数据类型，这默认DbType属性为NVarChar）可能这是执行insert命令时得到的确切错误消息

您可以尝试以下方法：

   Using cn As New SqlConnection(con.ConnectionString)
        con.Open()
        inscmd.Parameters.AddWitValue("@StaffInitials", lblStaffInitials.Text.Trim())
        inscmd.Parameters.AddWithValue("@Week", lblWeek.Text.Trim)
        inscmd.Parameters.AddWithValue("@Period", Convert.ToInt32(lblPeriod.Text.Trim))
        inscmd.Parameters.AddWithValue("@Day",lblDay.Text.Trim)
        inscmd.Parameters.AddWithValue("@Subject", lblSubject.Text.Trim)
        inscmd.Parameters.AddWithValue("@YearGroup", lblYear.Text.Trim)
        inscmd.Parameters.AddWithValue("@NumberOfPupils", Convert.ToInt32(lblNoOfPupils.Text.Trim))
        inscmd.Parameters.AddWithValue("@ControlledAssesment", lblControlledAssesment.Text.Trim)
        inscmd.Parameters.AddWithValue("@Room",lblRoom.Text.Trim)
        inscmd.Parameters.AddWithValue("@Session", txtSession.Text.Trim)

        inscmd.CommandText = "INSERT INTO Booking ([Week], [Day], [Period], [Subject], " +
                             "[YearGroup], [StaffInitials],[NumberOfPupils],[Session], " + 
                             "[Room],[ControlledAssesment]) "+
                             "VALUES " + 
                             "(@Week,@Day,@Period,@Subject,@YearGroup,@StaffInitials," +
                             "@NumberOfPupils,@Session,@Room,@ControlledAssesment)"
        inscmd.Connection = con
        inscmd.ExecuteNonQuery()
        inscmd.Parameters.Clear()
    End Using

我使用AddWithValue方法隐式创建一个带有DbType属性的参数，该属性派生自添加的值。因此，如果我添加一个字符串作为值，该参数将具有DbType.NVarchar，但如果我设置一个整数，则DbType将为DbType.Int。当然，这假设您的所有字段都是NVARChar类型，Period和NumberOfPupils除外。如果不是这样，您应该将适当的转换添加到参数

编辑：不确定，但我怀疑DAY是一个保留的关键字。最好用方括号封装列名

Answer 2

据我所知，问题出在数据库位置。

当程序被调试时，数据库副本放在bin / debug文件夹中，如果你在这里查看，你会看到副本，你的代码将直接到这个数据库并且不是原始数据库 （如果单击显示所有文件然后转到bin / debug文件，然后使用数据库浏览器打开，您可以看到上次调试/运行时估算的数据）

要解决此问题，您需要执行以下操作：

您的连接字符串

 con.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings("RoomBookingSystem.My.MySettings.Database1ConnectionString1").ConnectionString

将连接到前面提到的bin文件夹中的数据库。

您需要进入 app.config 文件，找到数据库的具体位置并将其用于连接字符串，这样您就可以从非拷贝中插入/更新数据数据库中。

在VB 2008中预订本地数据库的问题

2 个答案: