| As shown in Listing 1, you open a connection by calling the Open() method of the SqlConnection instance, conn. Any operations on a connection that was not yet opened will generate an exception. So, you must open the connection before using it.
如Listing1所示，打开连接需要调用SqlConnection实例conn的Open()方法。如果没有打开连接，任何对连接的操作都会产生异常。所以，你必须在使用连接之前打开它。
Before using a connection, you must let the ADO.NET code know which connection it needs. In Listing 1, we set the second parameter to the SqlCommand object with the SqlConnection object, conn. Any operations performed with the SqlCommand will use that connection.
在使用连接之前，你必须让ADO.NET代码知道它需要的连接。在Listing1中，我们将SqlCommand对象的第二个参数设置为SqlConnection对象conn。任何对SqlCommand对象的操作将使用此连接。
The code that uses the connection is a SqlCommand object, which performs a query on the Customers table. The result set is returned as a SqlDataReader and the while loop reads the first column from each row of the result set, which is the CustomerID column. We''''ll discuss the SqlCommand and SqlDataReader objects in later lessons. For right now, it is important for you to understand that these objects are using the SqlConnection object so they know what database to interact with.
使用连接的代码是SqlCommand对象，它执行对Customers表的查询。结果集被作为SqlDataReader返回，并且 上一页 [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] ... 下一页 >> | 
