private void AddProduct_Load(object sender, EventArgs e)
{
txtCountity.Text = "0";
txtPurchasesPrice.Text = "0";
txtSellingPrice.Text = "0";
System.Data.DataTable units_tbl = db.select(new string[] { "unit" }, "units", "unit");
System.Data.DataTable categorite = db.select(new string[] { "id", "category" }, "categories", "id");
cbx_category_id.DataSource = categorite.ColumnToArray(0);
cbx_category_name.DataSource = categorite.ColumnToArray(1);
cbx_unit.DataSource = db.select(new string[] { "unit" }, "units", "unit").ColumnToArray(0);
}