| SqlDataReader是对于大多数有效的情况下读取数据的好的方式。你不能使用它来写入数据。SqlDataReaders通常作为快速的只向前读的数据流。
You can read from SqlDataReader objects in a forward-only sequential manner. Once you''''ve read some data, you must save it because you will not be able to go back and read it again.
你能够以只向前的顺序方式从SqlDataReader对象中进行读取。只要你已经读取了某些数据，你必须保存它们，因为你将不能够返回并再一次读取它。
The forward only design of the SqlDataReader is what enables it to be fast. It doesn''''t have overhead associated with traversing the data or writing it back to the data source. Therefore, if your only requirement for a group of data is for reading one time and you want the fastest method possible, the SqlDataReader is the best choice. Also, if the amount of data you need to read is larger than what you would prefer to hold in memory beyond a single call, then the streaming behavior of the SqlDataReader would be a good choice.
SqlDataReader的只向前读的设计使它很迅速。它并没有遍历数据或者将数据重新写回给数据源的负担。因此，如果你一次只需要读一组数据，并且希望最快速的方法，SqlDataReader则是最好的选择。同样，如果一个单独调用所需要读取的数据量大于内存的存放能力，SqlDataReader的数据流形式应该是一个好的选择。
Note: Observe that I used the term "one time" in the previous paragraph when discussing the reasons why you would use a SqlDataReader. As with anything, there are exceptions. In many cases, it is more efficient to use a cached DataSet. While caching is outside the scope of this tutorial, we will discuss using DataSet objects in the next lesson.
注意：当讨论为什么应该使用SalDataReader的时候，我在上一段中使用的术语“一次”。任何事情，都有异常发生。在一些情况下，更有效的是使用缓存DataSet。因为缓存超出了本指南的范畴，我们将在下一节课“使用DataSet对象”中讨论它。
Creating a SqlDataReader Object
创建SqlDataReader对象
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