The DataReader is very easy to use. To get an instance of the DataReader object, you call the ExecuteReader() of the Command object, rather than using the DataAdapter . The ExecuteReader() returns a new instance of a DataReader object ready to display data starting at the first record returned. The code in Listing 8.2 (VB .NET) and in Listing 8.3 (C#) shows how to get a DataReader object.
Dim conn as New SqlConnection("Initial Catalog=Northwind;" + _ "Server=(local);UID=sa;PWD=;") Dim cmd as New SqlCommand("SELECT * FROM Employees", conn) Dim reader as SqlDataReader conn.Open() reader = cmd.ExecuteReader()
SqlConnection conn = new SqlConnection("Initial Catalog=Northwind;" + "Server=(local);UID=sa;PWD=;"); SqlCommand cmd = new SqlCommand("SELECT * FROM Employees", conn); SqlDataReader reader; conn.Open(); reader = cmd.ExecuteReader();
In Listings 8.2 and 8.3, line 1 instantiates a new connection object. Line 3 creates a new object of type SqlDataReader . The connection is then opened and a new SqlDataReader object is created using the ExecuteReader() method.
This is significantly easier than retrieving a DataSet ! Now that you know how to get a DataReader , it's time to see what the DataReader can do. In the next few sections, you'll see how to use the DataReader to step through database records and bind to Web controls.