how to display more than one record on datagridview

You should use a DataAdapter and use it to populate a DataTable.
Create a method for grabbing the data like this :

public DataTable GetDataTable()
{
  DataTable dt = new DataTable();

  using (SqlConnection con = new SqlConnection (@"YourConnectionString"))
  {
  using (SqlCommand cmd = new SqlCommand (query, con))
  {
  var adaptor = new SqlDataAdapter ();
  adaptor.SelectCommand = cmd;
  con.Open();
  adaptor.Fill(dt);
  return dt;
  }
  }
 }

Then You can reference it with your DataGrid :

DatagridView1.DataSource = GetDataTable();