Basics of ADO.NET

ADO.NET

• ASP.NET Web Applications
• Console Applications
• Windows Applications.

Various Connection Architectures

1. Connected architecture: the application remains connected with the database throughout the processing.
   
   
2. Disconnected architecture: the application automatically connects/disconnects during the processing. The application uses temporary data on the application side called a DataSet.

Understanding ADO.NET and it's class library

Important Classes in ADO.NET

1. Connection Class
2. Command Class
3. DataReader Class
4. DataAdaptor Class
5. DataSet.Class

1. Connection Class

2. Command Class

• ExecuteReader: Returns data to the client as rows. This would typically be an SQL select statement or a Stored Procedure that contains one or more select statements. This method returns a DataReader object that can be used to fill a DataTable object or used directly for printing reports and so forth.
  
• ExecuteNonQuery: Executes a command that changes the data in the database, such as an update, delete, or insert statement, or a Stored Procedure that contains one or more of these statements. This method returns an integer that is the number of rows affected by the query.
  
• ExecuteScalar: This method only returns a single value. This kind of query returns a count of rows or a calculated value.
  
• ExecuteXMLReader: (SqlClient classes only) Obtains data from an SQL Server 2000 database using an XML stream. Returns an XML Reader object.

3. DataReader Class