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ect is not null. If something goes wrong when instantiating the connection, it will be null and you want to make sure you don''''t try to close an invalid connection, which would generate an exception.
另外关闭连接的时候你应该预防的是确保连接对象非空。当实例化连接时出现错误，它将是null，而你确信不会试图关闭一个无效的连接，它应该会产生异常。
This example showed how to use a SqlConnection object with a SqlDataReader, which required explicitly closing the connection. However, when using a disconnected data model, you don''''t have to open and close the connection yourself. We''''ll see how this works in a future lesson when we look at the SqlDataAdapter object.
这个例子演示了如何通过SqlDataReader使用SqlConnection对象，它需要显式的关闭连接。然而，当使用断开连接模型的时候，并不需要你自己打开并关闭连接。当以后讲到SqlDataAdapter对象的时候我们将会看到它如何使用。
Summary
总结
SqlConnection objects let other ADO.NET code know what data base to connect to and how to make the connection. They are instantiated by passing a connection string with a set of key/value pairs that define the connection. The steps you use to manage the lifetime of a connection are create, open, pass, use, and close. Be sure to close your connection properly when you are done with it to ensure you don''''t have a connection resource leak.
SqlConnection对象让其它的ADO.NET代码知道连接哪一个数据库并且如何连接。它们通过传递一个使用键/值对定义的连接字符串来实例化。使用来管理连接的声明周期是创建、打开、传递、使用和关闭。当你完成了工作后确信适时的关闭连接，避免遇到连接资源泄漏的问题。
I hope you enjoyed this lesson and invite you to view the next one in this series, Lesson 03: The SqlCommand Object.
For further questions, you are welcome to participate in the C# Station Discussion Forums.
Your feedback is very important and I appreciate any constructive contributions you have. Please feel free to contact me for feedback or comments you may have about this lesson. << 上一页 [11] [12] 下一页
[Sql Server]第三课 SqlCommand对象(翻译)
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