最近剛學程式，我要到一個程式碼，目前只能大略看出一些輪廓，可是還是不太懂，
希望各為能幫我解答一下，執行結果應該會有500筆資料

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        
        public class Seat {
            public DateTime ptime { get; set; }
            public int Movie { get; set; }
            public string Seat_Num { get; set; }
            public int soldd { get; set; } //1 表　售出, 0 表未售出
            //流水號不用
        }
        static void Main(string[] args)
        {
            List<Seat> SeatList = new List<Seat>();
            for (int i = 0; i <= 500; i++) //產生500筆資料
            {
                SeatList.Add((new Seat
                {
                    ptime = DateTime.Now.AddDays(i),
                    Movie = i+100,
                    Seat_Num =i.ToString(),
                    soldd = 0
                }));
            }       
            string ConnString = "Data Source=127.0.1;Initial Catalog=Sample666;Integrated Security=True";
            SqlConnection conn = new SqlConnection(ConnString);
            DataTable dt = new DataTable();
            SqlCommand cmd = null;
            try
            {
                dt.Columns.Add("ptime", typeof(DateTime));
                dt.Columns.Add("movie", typeof(int));
                dt.Columns.Add("seat_num", typeof(string));
                dt.Columns.Add("sold", typeof(int));
                
                for (int i = 0; i < SeatList.Count; i++)
                {
                    DataRow dr = dt.NewRow();
                    //如果有空值會死掉
                    dr["ptime"] = SeatList[i].ptime;
                    dr["movie"] = SeatList[i].Movie;
                    dr["seat_num"] = SeatList[i].Seat_Num;
                    dr["sold"] = SeatList[i].soldd;
                    dt.Rows.Add(dr);
                }
                conn.Open();
                using (SqlBulkCopy sqlBC = new SqlBulkCopy(conn))
                {
                    sqlBC.ColumnMappings.Add("ptime", "ptime");
                    sqlBC.ColumnMappings.Add("movie", "movie");
                    sqlBC.ColumnMappings.Add("seat_num", "seat_num");
                    sqlBC.ColumnMappings.Add("sold", "sold");
                    sqlBC.BatchSize = SeatList.Count;
                    sqlBC.BulkCopyTimeout = 60;
                    sqlBC.DestinationTableName = "[seats]";
                    sqlBC.WriteToServer(dt);
                }
            }
            catch (Exception ex)
            {
             
            }
            finally
            {
                conn.Dispose();
            }

        }
    }
}

第一個for回圈我知道是產生500筆資料，可是第2個for回圈的用意是什麼?我只知道
說他是空值就會error，但還是不太清楚這迴圈的用意，希望能為我講解一下，謝謝。