Question

当我运行此功能时

    For RepeatBooking = 1 To 51
        dateConvertedDateToBook = dateDateToBook.Date
        dateDateToBook = dateDateToBook.AddDays(7)
        strDateToBook = dateConvertedDateToBook.ToString("yyyy-MM-dd")

        Try
            Dim command As MySqlCommand = New MySqlCommand
            Dim sqlQuery As String = "INSERT INTO bookings SET Date=" & "'" & strDateToBook & "',RoomID='" & strComputerRoomToBook & "',Length='" & intNewBookingLength & "',Period='" & intNewStartPeriod & "',UserID='" & intid & "'"
            Dim reader As MySqlDataReader
            SQLConnection.Open()
            command.CommandText = sqlQuery
            command.Connection = SQLConnection
            reader = command.ExecuteReader
            SQLConnection.Close()
        Catch excep As Exception
            MsgBox(excep.ToString)
        End Try

    Next

在我的程序中，我收到错误消息“连接属性尚未设置或为空” 我怎么能摆脱这个？

当它到达SQLconnection.Open（）时会转到异常我在模块的顶部创建了ServerString和MySQL连接，如下所示：

Dim ServerString As String = "Server=localhost;User Id=root;Password=**********;Database=rooms"
Dim SQLConnection As MySqlConnection = New MySqlConnection

Answer 1

您正在打开没有其属性的连接它应该是，

Dim SQLConnection As New MySqlConnection(ServerString)
SQLConnection.Open

此外，您可能希望使用USING功能，以便正确关闭您的连接您似乎只是在数据库中插入了一堆值而没有检索任何内容，为什么要使用DataReader呢？你的代码应该是这样的：

Using SQLConnection = New MySqlConnection(ServerString)  
    SQLConnection.Open  'You should open a connection only once
    For RepeatBooking = 1 To 51
        dateConvertedDateToBook = dateDateToBook.Date
        dateDateToBook = dateDateToBook.AddDays(7)
        strDateToBook = dateConvertedDateToBook.ToString("yyyy-MM-dd")
        Try
            Dim sqlQuery As String = "INSERT INTO bookings SET " & _ 
                "Date='" & strDateToBook & "'," & _
                "RoomID='" & strComputerRoomToBook & "', " & _
                "Length='" & intNewBookingLength & "', " & _
                "Period='" & intNewStartPeriod & "', " & _
                "UserID='" & intid & "'"
            Dim command = New MySqlCommand(sqlQuery, SQLConnection)
            command.ExecuteNonQuery
        Catch excep As Exception
            MsgBox(excep.Message)
        End Try  
     Next  
End Using

此外，您可能希望更改将值传递给参数的方式。这将阻止SQL注入。

连接属性尚未设置或为null

1 个答案: