An Easy Way To Query a Database

You are both wrong with the DataAdapter. Why do you think there is an overload with the querystring and the connectionstring?

public DataSet select_query(string query, string con_str)
{
  try
  {
         using (SqlDataAdapter da = new SqlDataAdapter(query,con_str))
         {
           DataSet ds = new DataSet();
           da.Fill(ds);  // Automatically opens/closes connection.
           return ds;
         }
       }
       catch (Exception ex)
       {
            MessageBox.Show(ex.Message);  // Bad mojo, but better than nothing I guess.
            return null;
       }
}