Check dataset is empty or not

Question

This is working for me just fine. With if checks if dataset is empty or not. If so, return null value. But is the check of dataset right way or should i do some other way?

 da2 = new SqlDataAdapter("SELECT project_id FROM project WHERE _small_project_id = '" + cb_small_project.SelectedValue + "' ORDER BY NEWID()", conn);
 ds2 = new DataSet();
 da2.Fill(ds2);
 DataRow[] rowProject = dt2.Select();

 if (ds2.Tables[0].Rows.Count == 0)
    cmd.Parameters["@_project_id"].Value = guidNull;
 else
    cmd.Parameters["@_project_id"].Value = rowProject[0]["project_id"];

Answer 1

This Worked for me.... and won't give exception....

foreach (DataTable table in ds.Tables)
   if (table.Rows.Count != 0)
      table.Dispose();

Answer 2

In my opinion the 'right' way is to check both:

ds2.Tables.Count 

ds2.Tables[0].Rows.Count