连接属性尚未设置或为null

When I run this function

当我运行这个功能

    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
    For R