C#中如何显示在Datagridview中显示users表中的所有信息，最好是三层架构模式！

采用三层架构的模式，在Datagridview中显示users表中的所有信息！急！！！

private void Form1_Load(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("Server=WWW-2270B8786BB;Integrated Security=SSPI;Database=Northwind;Uid=sa;Pwd=sa;");
string sqlStr = "select * from Orders";
SqlCommand cmd = new SqlCommand(sqlStr, conn);
SqlDataAdapter da = new SqlDataAdapter(cmd);

DataSet ds = new DataSet();
da.Fill(ds);
this.dataGridView1.DataSource = ds.Tables[0];

}

sqlHelp层 public DataSet GetDs(string sqlText) { OpenConnection(); SqlDataAdapter sda = new SqlDataAdapter(sqlText, con); DataSet ds = new DataSet(); sda.Fill(ds); CloseConnection(); return ds; }

dal层 public DataSet show1() { string sql = "select *from users"; return help.GetDs(sql); }

bll层 public DataTable ShowInfo() { return dal.show1().Tables[0]; }

UI 直接调用BLL绑定