public static void DeleteDependencies(long id)
    {
        var ctx = new DataClassesDataContext();

        // LabOrder's dependency is LabOrderDetail
        var labOrderDetails = from l in ctx.LabOrderDetails
                              where l.LabOrderID == id
                              select l;

        foreach (var labOrderDetail in labOrderDetails)
        {
            LabOrderDetailOperations.DeleteDependencies(labOrderDetail.ID);
        }
        ctx.LabOrderDetails.DeleteAllOnSubmit(labOrderDetails);

        // submit changes
        ctx.SubmitChanges();
    }
    public static void DeleteDependencies(long id)
    {
        // medical service has dependency lab order detail
        var ctx = new DataClassesDataContext();

        var labOrderDetails = from l in ctx.LabOrderDetails
                              where l.MedicalServiceID == id
                              select l;

        foreach (var labOrderDetail in labOrderDetails)
        {
            LabOrderDetailOperations.DeleteDependencies(labOrderDetail.ID);
        }
        ctx.LabOrderDetails.DeleteAllOnSubmit(labOrderDetails);

        //submit changes
        ctx.SubmitChanges();
    }