数据库交互的几个简单的对象
以前曾经写过几篇关于.net对SQL SERVER编程中用到的几个对象，发现理解的不是很深刻，今天在这里在总结一下。 为何还会总结呢？ 因为试想无论是做WEB开发还是桌面应用程序，都离不开与数据库打交道（增、删、改、查）。无非就是这些操作，变化的只是前段页面
以前曾经写过几篇关于.net对SQL SERVER编程中用到的几个对象，发现理解的不是很深刻，今天在这里在总结一下。
为何还会总结呢？
因为试想无论是做WEB开发还是桌面应用程序，都离不开与数据库打交道（增、删、改、查）。无非就是这些操作，变化的只是前段页面，后台与数据库的交互是始终不变的。
无论是B/S还是所谓的C/S后台都是一回事，所以只要把后台数据库交互部分设置好了，工程就完成了一多半了。
常用对象
SqlConnection：表示一个到 SQL Server 数据库的打开的连接。 此类不能被继承。
ConnectionState：描述与数据源的连接的当前状态。
SqlCommand：表示要对 SQL Server 数据库执行的一个 Transact-SQL 语句或存储过程。 此类不能被继承。
SqlParameter：表示 SqlCommand 的参数。
SqlDataReader：提供一种从数据库读取行的只进流方式。
DataSet：表示一个存放于内存中的数据缓存。
SqlDataAdapter：表示用于填充 DataSet 和更新 SQL Server 数据库的一组数据命令和一个数据库连接。
这么多对象，如何来理解呢？看下面一副图片。
我们把上述的部分划分为两个部分来理解，就简单易懂了。
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