Fundamentally, almost all business applications need some type of access to data. In addition, many a time, business components need to interact with each other using XML and XML based Internet services. This is where ADO.NET comes into picture.
Microsoft has provided us with several high level data access API's.
The data access method called Data Access Objects or more popularly known as DAO was primarily intended for jet databases and was optimized for it although it could be used for ODBC based data sources.
In order to deal with server based databases more efficiently, Microsoft built a wrapper on top of ODBC. It was called Remote Data Objects (RDO), and it provided an object model similar to DAO. Unfortunately, as the objects could not be marshalled across the net, it was of limited use.
DAO and RDO both used the API approach for accessing data. Microsoft wanted to use a COM based approach to data access, and the result was OleDB and ADO. ADO is the OLE automation implementation built on top of OleDB. ADO was first introduced with the first version of ASP. The primary advantage with ADO was improved support for disconnected data and the ability for a disconnected recordset to marshall over the network.
Microsoft decided to create a database access model to go with the .NET Framework. It mainly focuses on the following key goals:
- XML integration
- Disconnected data model
[NOTE] Although similar in concept, ADO.NET has different functionality from ADO. Experienced VB programmers will find that more often than not, they will not be using the recordets they are familiar with. ADO.NET introduces quite a few objects used for data access in various manners and conditions. [End Note]
ADO.NET is broken down into 3 namespaces in the .NET framework. Namespaces are used to organize components into groups based on organizational and logical reasons.
In previous versions of ADO, an attempt was made to create as generic methods as possible, whereas with ADO.NET, the data provider classes for SQL server are now optimized. Optimized data providers for specific database products can now be created also.
From a developers point of view, objects provided by OleDB managed providers and SQL server managed providers are quite similar, the only difference being they are prefixed with SQL rather than OleDB.
Let's now see how to use ADO.NET in an application. We will use the Pubs sample database that is included with SQL server 2000. We will use the Authors, Publishers, Titles and TitleAuthor tables. Although we will use OleDB managed providers, the same code can be used for SQL managed providers very easily. You can even use access tables in place of SQL tables if you do not have SQL tables.