数据访问
System.Data.SqlClient
l 与 framework 中的 API 一致，除以下几方面
Ø 无连接池
Ø 无分布式事务
Ø 无加密的连接
Ø 必须通过 TCP/IP 连接
l Windows 认证
Ø 必须在 connection 字符串中提供身份信息

| Working with SQL Server from a device is no different from a coding standpoint than from a desktop application. There are however, some features that are unavailable from devices.
| Connection pooling, distributed transactions, and encrypted connections are not supported. You can create transactions on a single database, but transactions cannot span multiple databases.
| Another important consideration is that SQL Server connections are only supported through TCP/IP connections. Devices connected through a serial connection to a workstation can not access remote SQL Servers.
| Also, while devices can use Windows Authentication to log into a SQL Server, the users credentials must always be passed in the connection string.
| Aside from these issues, the process of opening connections and executing commands is no different. While SQL Server provides a great mechanism for storing data remotely, it can not be used on a device to store local data. To do this, you must use SQL Server CE.