private void completezFurnizori()
{
comboBoxFurnizor.Items.Clear();
furnizoriDT = Interogari_DB.selectezFurnizor();
comboBoxFurnizor.DataSource = furnizoriDT;
comboBoxFurnizor.ValueMember = "cod_furnizor";
comboBoxFurnizor.DisplayMember = "denumire";
}