Introduction to ADO.NET
The .NET
data access layer is called ADO.NET and consists of two major ways of
dealing with data. The first way, and the easiest for developers
familiar with SQL, is implemented in terms of the
IDataReader interface. The second way is the
DataSet.
Out of the box, .NET Framework Version
1.0 provides implementations of IDataReader in
System.Data.SqlClient.SqlDataReader (for SQL
Server data sources) and
System.Data.OleDb.OleDbDataReader (for OLE data
sources). .NET 1.1 adds the System.Data.Odbc and
System.Data.OracleClient namespaces for access to
ODBC and Oracle databases, respectively.
Tip
In fact, most of the classes in the
System.Data.OleDb and
System.Data.SqlClient namespaces simply provide
implementations of interfaces in the System.Data
namespace, so I’ll just refer to the interfaces by
their interface names, such as IDataReader, until
we get down to examples. If you want to learn more about ADO.NET, I
suggest ADO.NET in a Nutshell, by Bill Hamilton
and Matthew MacDonald (O’Reilly).
Before you can actually use the
IDataReader to read data, you need to set up a
connection to the database using the IDbConnection
interface. Exactly how you do that depends on whether
you’re using the SqlConnection or
the OleDbConnection, but each one has a
ConnectionString property that you can use to
specify the database you’re connecting to.
Creating an
IDbConnection does not actually create the physical connection to the database. In fact, you can wait until the ...
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