一直认为数据库访问比本地文件访问是要慢很多的，但究竟慢多少却不清楚。终于忍不住作了下比较测试。

测试环境：OS---Windows 2000 Server DatabaseServer----SQLServer 2000 程序语言：CSharp

测试方式：从数据库中读取参数表/从XML中读取配置参数等同数量的记录并实例化对象。

测试程序如下：

using System;
using System.Globalization;
using System.IO;
using System.XML.Serialization;
using System.XML;
using System.Data;
using System.Data.SqlClient;

public class Demo
{
public static void Main()
{
System.Console.WriteLine("===== ExecuteXML() =====================================");
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine(ExecuteXML());
System.Console.WriteLine("========================================================");

System.Console.WriteLine("===== ExecuteSQL() =====================================");
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine(ExecuteSQL());
System.Console.WriteLine("========================================================\n");

}

static double ExecuteSQL()
{
string _connString = "server=data-server;user id=sa;password=1234;database=LeadDB;min pool size=4;max pool size=4;packet size=3072";
SqlCommand cmd = new SqlCommand();
SqlConnection conn = new SqlConnection(_connString);

double begin = CultureInfo.InvariantCulture.Calendar.GetMilliseconds(DateTime.Now);
try {
conn.Open();

cmd.Connection = conn;
cmd.CommandText = "SELECT [CategoryId], [Name] FROM [SYS_Category] WHERE [CategoryType] = 2";

cmd.CommandType = CommandType.Text;
SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
while (rdr.Read())
{
new Entity(rdr.GetInt32(0), rdr.GetString(1));
}
rdr.Close();
}catch {
conn.Close();
throw;
}
begin = CultureInfo.InvariantCulture.Calendar.GetMilliseconds(DateTime.Now) - begin;
return (begin >= 0)?begin:begin+1000.0;
}

static double ExecuteXML()
{
double begin = CultureInfo.InvariantCulture.Calendar.GetMilliseconds(DateTime.Now);
XMLDocument XMLDoc = new XMLDocument();
XMLDoc.Load( @"F:\LeadBridge\XCERP\Web\OnlineService\SYS_Category_Headship.XML" );

foreach(XMLNode node in XMLDoc.SelectNodes("items/item")){
new Entity(int.Parse(node.Attributes["id"].Value), node.InnerText);
}
begin = CultureInfo.InvariantCulture.Calendar.GetMilliseconds(DateTime.Now) - begin;
return (begin >= 0)?begin:begin+1000.0;
}
}

public class Entity {
public Entity(int age, string name){
this._Age = age;
this._Name = name;
}
private int _Age;
private string _Name;
public int Age{
get{ return _Age; }