DataSet虚拟表中为空??请高手赐教!!

if (DBHelper.addEmployee.Text == "UPDEmployeeForm")
{
string sql = string.Format("select * from Employee inner join Deportment on Employee.EDID=Deportment.DID where EID='{0}'",DBHelper.str);
SqlDataAdapter da = new SqlDataAdapter(sql, DBHelper.con);
DataSet ds = new DataSet();
da.Fill(ds, "UPDEmployee");
foreach (DataRow dr in ds.Tables["Employee"].Rows) //运行到这一步就报错了
{
DBHelper.addEmployee.txtName.Text = dr["EName"].ToString();
DBHelper.addEmployee.txtEID.Text = dr["EID"].ToString();
DBHelper.addEmployee.txtAge.Text = dr["EAge"].ToString();
DBHelper.addEmployee.cboSex.Text = dr["ESex"].ToString();
DBHelper.addEmployee.cboDeportment.Text = dr["DID"].ToString();
}
}

foreach (DataRow dr in ds.Tables["Employee"].Rows)

把这句改成：

foreach (DataRow dr in ds.Tables[0].Rows)