private void button5_Click(object sender, EventArgs e)
        {
            if (dataGridView1.Rows.Count <= 0)
            {
                MessageBox.Show("Tidak ada data untuk di simpan", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else
            {
                db_Form_Penjualan_Eceran fe = new db_Form_Penjualan_Eceran()
                {
                    No_Form_Penjualan_Eceran = textBox6.Text,
                    ID_Karyawan = textBox1.Text,
                    Tanggal     = dateTimePicker1.Text
                };
                db.AddTodb_Form_Penjualan_Eceran(fe);
                db.SaveChanges();


                for (int i = 0; i < dataGridView1.RowCount; i++)
                {
                    string ih = "";
                    string ah = "";
                    int    h = 0, l = 0;
                    try
                    {
                        ih = dataGridView1.Rows[i].Cells[1].Value.ToString();
                        h  = int.Parse(dataGridView1.Rows[i].Cells[3].Value.ToString());
                        l  = int.Parse(dataGridView1.Rows[i].Cells[4].Value.ToString());
                        ah = dataGridView1.Rows[i].Cells[2].Value.ToString();
                    }
                    catch (Exception) { }

                    db_Detail_Form_Penjualan_Eceran dfe = new db_Detail_Form_Penjualan_Eceran()
                    {
                        No_Form_Penjualan_Eceran = textBox6.Text,
                        ID_Barang   = ih,
                        Harga       = h,
                        Jumlah      = l,
                        Nama_Barang = ah
                    };
                    db.AddTodb_Detail_Form_Penjualan_Eceran(dfe);
                    db.SaveChanges();



                    try
                    {
                        var up = (from a in db.db_Barang where a.ID_Barang == ih select a).FirstOrDefault();
                        if (up.Stock != null)
                        {
                            up.Stock = up.Stock - l;
                            db.SaveChanges();
                            if (up.Stock <= 500)
                            {
                                MessageBox.Show("Stock " + dataGridView1.Rows[i].Cells[2].Value.ToString() + " mulai menipis, harap segera buat Faktur Pemesanan! ", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                            }
                        }
                    }
                    catch (Exception) { }
                }
                MessageBox.Show("Transaksi berhasil", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                button4.Enabled = false;
                button5.Enabled = false;
                button6.Enabled = false;
                id = textBox6.Text;
            }
        }