private void button1_Click_1(object sender, EventArgs e)
 {
     DbHelper.ExportExcel(dataGridView1);
 }
        private void btluu_Click(object sender, EventArgs e)
        {
            if (validate())
            {
                if (state == "insert")
                {
                    //MessageBox.Show("INSERT INTO PhieuNhap(MaPhieuNhap, TenNCC, TenMH, SoLuongNhap,GiaNhap,TienDaThanhToan,NgayThanhToan) VALUES (" + Convert.ToInt32(txtMaPhieuNhap.Text) + ",N'" + txtTenNCC.Text + "',N'" + txtTenMH.Text + "'," + Convert.ToInt32(txtSoLuongNhap.Text) + "," + Convert.ToInt32(txtGiaNhap.Text) + "," + Convert.ToInt32(txtTienDaThanhToan.Text) + ",'"+txtNgayThanhToan.Value.ToShortDateString().ToString() +"')");
                    string sql = @"INSERT INTO [QLKhoHang].[dbo].[PhieuXuat]
           ([NgayXuat]
           ,[NguoiXuat]
           ,[MaKH]
           ,[SoLuongXuat]
           ,[MaHH])
     VALUES
           ('" + fieldNgayXuat.Value.ToString("yyyy/MM/dd") + @"'
           ,N'" + fieldNguoiXuat.Text + @"'
           ," + fieldMaKH.SelectedValue + @"
           ," + Convert.ToInt64(fieldSoLuongXuat.Text) + @"
           ," + fieldMaHH.SelectedValue + @"
)";

                    if (DbHelper.Query(sql) != -1)
                    {
                        MessageBox.Show("Thêm thành công !");
                    }
                    else
                    {
                        MessageBox.Show("Có lỗi trong quá trình thêm");
                    }
                }
                //end add
                else if (state == "update")
                {
                    string sql = @"UPDATE [QLKhoHang].[dbo].[PhieuXuat]
   SET [NgayXuat] ='" + fieldNgayXuat.Value.ToString("yyyy/MM/dd") + @"'
      ,[NguoiXuat] = N'" + fieldNguoiXuat.Text + @"'
      ,[MaKH] =" + fieldMaKH.SelectedValue + @"
      ,[SoLuongXuat] =" + Convert.ToInt64(fieldSoLuongXuat.Text) + @"
      ,[MaHH] = " + fieldMaHH.SelectedValue + @"
 WHERE MaPXK = " + Convert.ToInt64(fieldMaPXK.Text);



                    if (DbHelper.Query(sql) != -1)
                    {
                        MessageBox.Show("Sửa thành công !");
                    }
                    else
                    {
                        MessageBox.Show("Có lỗi trong quá trình Sửa");
                    }
                }

                hien();
                dongtxt();
                mobtn();
            }//end validate
            if (state == "delete" && validate())
            {
                string sql = @"DELETE [QLKhoHang].[dbo].[PhieuXuat] WHERE MaPXK = " + Convert.ToInt64(fieldMaPXK.Text);

                if (DbHelper.Query(sql) != -1)
                {
                    MessageBox.Show("Xóa thành công !");
                }
                else
                {
                    MessageBox.Show("Có lỗi trong quá trình Xóa");
                }

                hien();
                dongtxt();
                mobtn();
            }
        }