什么是Asp.Net应用程序
ASP.NET defines an application as the sum of all files, pages, handlers, modules, and executable code that can be invoked or run in the scope of a given virtual directory (and its subdirectories) on a Web application server. For example, an "order" application might be published in the "/order" virtual directory on a Web server computer. For IIS the virtual directory can be set up in the Internet Services Manager; it contains all subdirectories, unless the subdirectories are virtual directories themselves.
Each ASP.NET Framework application on a Web server is executed within a unique .NET Framework application domain, which guarantees class isolation (no versioning or naming conflicts), security sandboxing (preventing access to certain machine or network resources), and static variable isolation.
ASP.NET maintains a pool of HttpApplication instances over the course of a Web application's lifetime. ASP.NET automatically assigns one of these instances to process each incoming HTTP request that is received by the application. The particular HttpApplication instance assigned is responsible for managing the entire lifetime of the request and is reused only after the request has been completed. This means that user code within the HttpApplication does not need to be reentrant.
相关文档：
http://www.cnblogs.com/TerryFeng/archive/2009/02/01/1382123.html
这很常用，搜索了一下博客园的“找找看”和谷歌，看到大部分都是转载于一两篇文章（而且来源还不是博客园），有的是简单的说一点无法运行，给初学者的调试和学习带来不方便，我在这里将jQuery Ajax 调用Aspx.Net WebService 的几个常用的方法 ......
第一:
Response.Write(<script></script>);
第二:
托一个Literal控件
Literal(控件名).Text="<script></script>";
......
我们经常要在一个表中将数据迁移到另一个表，当然，用的方法十分多了。在.net 2.0中，提供了一个sqlbulkcopy类，也可以实现如下的操作，下面简单介绍下。比如一个表如下
CREATE TABLE Person3
(
PersonID int IDENTITY(1,1) PRIMARY KEY,
Name nvarchar(200),
Email nvarchar(200),
Picture image
)
INSERT INT ......
1. 数据库访问性能优化
数据库的连接和关闭
访问数据库资源需要创建连接、打开连接和关闭连接几个操作。这些过程需要多次与数据库交换信息以通过身份验证，比较耗费服务器资源。ASP.NET中提供了连接池(Connection Pool)改善打开和关闭数据库对性能的影响。系统将用户的数据库连接放在连接池中，需要时取出，关闭时� ......
