private void button4_Click(object sender, EventArgs e)
        {
            dateform form_d = new dateform("prod_buy", "date_buy");

            form_d.ShowDialog();
            if (form_d.sql != null)
            {
                dataGridView1.DataSource            = DataBase1.ConnectData(form_d.sql, "table4");
                dataGridView1.Columns[0].HeaderText = "Сума за період";
            }
            //form_del.ValuesDeleted += new ValuesDeletedHandler(ShowTable);
        }
        private void button4_Click(object sender, EventArgs e)
        {
            dateform form_d = new dateform("electro", "date_elect");

            form_d.ShowDialog();
            // if (form_d.sql != null)
            // {select avgprice('10.10.2011','27.10.2011') from dual
            if (form_d.sql != null)
            {
                dataGridView1.DataSource            = DataBase1.ConnectData(form_d.sql, "table4");
                dataGridView1.Columns[0].HeaderText = "Сума за період";
            }
            // }
        }