用VC轻松实现 ADO.net
本文示例源代码或素材下载 本文编译器使用Visual Studio 2005 数据库使用SQL Server 2005 express .net版本为2.0 一、实现模型 ADO.net对每种数据库都提供了专门的连接字，不过每种的连接方式都差不多，所以这里我只用SQL Server来做。我在连接数据库时使用
本文示例源代码或素材下载
本文编译器使用Visual Studio 2005 数据库使用SQL Server 2005 express .net版本为2.0
一、实现模型
ADO.net对每种数据库都提供了专门的连接字，不过每种的连接方式都差不多，所以这里我只用SQL Server来做。我在连接数据库时使用了以下几个步骤：
1.连接数据源
使用Connection对象来连接，对于具体的数据库可用具体的对象，如SQL Server可用SqlConnection对象，不过要注意版本问题。
2.检索需要的数据
使用DataAdapter对象来检索，对于具体的数据库同样可用具体的对象，将来对数据的修改也用到它。
3.将数据填充到本地
使用DataAdapter对象的Fill方法，可以填充到DataSet对象中去。
4.显示数据
使用DataGridView对象可以轻松显示、修改DataSet中的数据。注意ListBox/ListView不再有Report方式。
5.需要注意的地方
将关系定义到客户端上，可以减少和服务器的通信量及服务器的运算压力，从而提升性能。
保存主键及唯一关系需要设置一下DataAdapter对象的MissingSchemaAction属性，但是外键关系必须手动添加到DataSet对象的Relations属性
DataAdapter对象的Fill()方法会自动调用Connection对象的Open()和Close()。
DataAdapter的UpdateBatchSize属性可以将指定数量的命令捆绑起来发送到服务器(减少了通信次数，降低了通信冗余)从而提高性能，但是太高反而会因网络等原因降低性能，默认值为1(禁用)，详见MSDN。
DataSet功能十分强大，例如GetXml()方法将数据以可阅读的XML方式输出，GetXmlSchema()方法则输出关系，非常好用。
对象简介Connection
连接数据库的最底层对象，要对它设置连接字。
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