private void SanPhamForm_Load(object sender, EventArgs e)
{
string strMaDM = MainForm.strMaDanhMuc_Chon;
tbSP = objSP.GetSanPhamByMADM(strMaDM);
dataGridView1.DataSource = tbSP;
cboDanhMuc.DataSource = objDM.GetDanhMuc();
cboDanhMuc.DisplayMember = "TenDM";
cboDanhMuc.ValueMember = "MaDM";
cboDanhMuc.SelectedIndex = -1;
}