private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) { dataGridView1.Rows.Clear(); try { int a = int.Parse(comboBox1.SelectedValue.ToString()); DataTable dt = bllss4.getPartBySource(a); comboBox3.DataSource = dt; comboBox3.DisplayMember = "PartName"; comboBox3.ValueMember = "PartID"; } catch (Exception) { } }