SqlDataAdapter的DeleteCommand属性

Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            SqlConnection conn = new SqlConnection("Server=zhuobin;uid=sa;pwd=zhuobin;database=Northwind");
            string qry = @"select * from employees where country='UK'";
            string del = @"delete from employees where employeeid=@employeeid";
            try
            { 
               //Create the adapter
                SqlDataAdapter da = new SqlDataAdapter();
                da.SelectCommand = new SqlCommand(qry,conn);
                //Create the DataSet
                DataSet ds = new DataSet();
                da.Fill(ds,"Employees");
                //get data Table reference
                DataTable dt=ds.Tables["employees"];
                //Create the Command
                SqlCommand cmd = new SqlCommand(del,conn);
                cmd.Parameters.Add("@employeeid",SqlDbType.Int,4,"employeeid");
                string filter = @"firstname='Roy' and lastname='Beatty'";
                //delete employees
                foreach (DataRow row in dt.Select(filter))
                {
                    row.Delete();
                }
                da.DeleteCommand = cmd;
                da.Update(ds,"employees");
                foreach (DataRow row in dt.Rows)
                {
                    Console.WriteLine("{0}{1}{2}",row["firstname"].ToString().PadRight(15),row["lastname"].ToString().PadLeft(25),row["city"]);
                }


            }
            catch (SqlException ex)
            {
                Console.WriteLine("The error:{0}", ex.Message);
            }
            finally
            {
                conn.Close();
            } Console.ReadLine();
        }
    }
}