Как сделать SQL запрос в C# на обновление связанных таблиц?

Не могу создать запрос на обновление данных в таблице, обновляться может только столбец Salary, все остальные столбцы (ID и тип недвижимости) либо скрыты от пользователя, либо ReadOnly. А на деле обновляться должна только таблица Offers.

    //обновление
    public static DataTable UpdateDataOffers(DataTable dtable)
    {
        DataTable rtable = null;
        using (Connection = new SqlConnection(connectionStringToDatabase))
        {
            Command = Connection.CreateCommand();
            Command.CommandText = "";
            Adapter = new SqlDataAdapter(Command);
            CommandBuilder = new SqlCommandBuilder(Adapter);
            Adapter.Update(dtable);
            rtable = dtable;
        }
        return rtable;
    }

    //код на подгрузку данных в DataGridView
    public static DataTable LoadingOffers(Clients ClientObj)
    {
        using (Connection = new SqlConnection(connectionStringToDatabase))
        {
            Connection.Open();
            Command = new SqlCommand("SELECT Offers.ID_offer, Offers.ID_realtor, Offers.ID_client, CONCAT(Realtors.Surname, ' ', Realtors.Name) AS [Риелтор], Objects_real_estate.TypeObjectName AS [Тип недвижимости], Offers.Salary AS [Стоимость] " +
            "FROM(((Offers INNER JOIN Realtors ON Offers.ID_realtor = Realtors.ID_realtor) INNER JOIN Objects_real_estate ON Objects_real_estate.ID_object_real_estate = Offers.ID_object_real_estate) " +
            $"INNER JOIN Clients ON Clients.ID_client = Offers.ID_client) WHERE Offers.ID_client = {ClientObj.ID}", Connection);
            Adapter = new SqlDataAdapter(Command);
            dataSet = new DataSet();
            Adapter.Fill(dataSet);
            Connection.Close();
        }
        return dataSet.Tables[0];
    }