populating other columns of gridview based on first column

Question

hello everybody how can Auto populating other columns of the gridview based on the value in the first column

i try this code but it gets error

private void dataGridView1_CellValidated(object sender, DataGridViewCellEventArgs e)
  {
  int count = dataGridView1.Columns.Count;
  if (e.RowIndex >= 0)
  {
  if (!string.IsNullOrEmpty(dataGridView1.Rows[e.RowIndex].Cells[2].Value.ToString()))
  {
  id1 = int.Parse(dataGridView1.Rows[e.RowIndex].Cells[2].Value.ToString());
  populateColumns();
 
  dataGridView1.Rows[e.RowIndex].Cells[4].Value = barcode;
  dataGridView1.Rows[e.RowIndex].Cells[5].Value = price;
  dataGridView1.Rows[e.RowIndex].Cells[6].Value = unit;
  }
  }
 
  }
 

 
  private void populateColumns()
  {OleDbConnection conConnect = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Application.StartupPath + "\\Store.mdb");
  {
  string str = "SELECT Product.ID, Units.Unit, Product.barcode, Product.price FROM Units INNER JOIN Product ON Units.Un_id = Product.Un_id  WHERE proname " +
  id1 + "';";
  OleDbCommand cmd =
  new OleDbCommand(str, conConnect);
  OleDbDataAdapter da = new OleDbDataAdapter();
  da.SelectCommand = cmd;
  DataSet ds = new DataSet("dsEmployee");
  da.Fill(ds);
 
  conConnect.Open();
 
  foreach (DataRow row in ds.Tables[0].Rows)
  {
  try
  {
  barcode = row["barcode"].ToString();
  price = row["price"].ToString();
  unit = row["Unit"].ToString();
  }
  catch (FormatException fEx)
  {
  MessageBox.Show(fEx.Message);
  }
  }
  }
  }


the error is Object reference not set to an instance of an object.null referance unhandle how it can be done