1. 1 Introduction to ADO.NET Microsoft ADO.NET 2.0 Step by Step Rebecca M Riordan Microsoft Press, 2006

2. 2 Introduction to ADO.NET “Active Data Objects” A set of class defintions included in the.NET Framework Objects collaborate to provide.NET applications (relatively) easy access to databases. Designed for scalability. 100’s or 1000’s of clients on a database server Offload functionality from server to client

3. 3 The ADO.NET Object Model Adapter Command Reader Connection DataSet DATABASEDATABASE CLIENTCLIENT Data Provider ADO.NET Handles communication with a physical data store. The actual data Knows how to do SQL commands on the database A light weight object for sequential read-only access to a query result. Provides general disconnected access to data http://msdn.microsoft.com/en-us/library/a6cd7c08.aspx

4. 4 Data Provider Collection of Class Definitions Specific to a data source MS SQL Server Oracle (others) Same set of classes for each data source Class name differs SqlDataConnection vs OracleDataConnection SqlCommand vs OracleCommand etc.

5. 5 Data Provider Objects Connection Controls communication with data source Properties: ConnectionString Identifies server and database User ID and password (if external) Methods Open Close

6. 6 Connection String MS SQL Server Examples connStr = "server=scorpius.eng.usf.edu; User ID=turnerr; Password=xxxxxxx" connStr = "server=mssql06.discountasp.net; database=DB_110074; User ID=rollinsturn; Password=xxxxx" connStr = "server=(local)\\VSDOTNET; database=Bulk_Mail_Addresses; Trusted_Connection=yes";

7. 7 Data Provider Objects Command Object Knows how to execute a SQL command on a server Properties: CommandText A SQL statement to be executed at the data source. SqlCommand1.CommandText = "SELECT * FROM Address_List"; Can be changed by the program. Methods ExecuteReader ExecuteScalar ExecuteNonquery

8. 8 Data Provider Objects DataReader A fast, low-overhead object, similar to a StreamReader for file input. Provides forward-only, read-only stream of data from a data source Created by calling the ExecuteReader method of a Command object Never with “new” Connection must remain open while the DataReader is used.

9. 9 Data Provider Objects There are two kinds of “Adapters” Data Adapter Present in ADO 1.0 Continued in ADO 2.1 Table Adapter New in ADO 2.0

10. 10 DataAdapter Provides access to a collection of data from a data source Pemits client to close connection while processing the data. Effectively provides a local cache Client accesses the cache rather than the actual database. Actual database can be updated when desired.

11. 11 Table Adapter Includes a DataAdapter and a Connection object. Improves functionality and ease of use of the original DataAdapter.

12. 12 Data Provider Objects DataAdapter Contains four Command Objects: SelectCommand UpdateCommand InsertCommand DeleteCommand Uses SelectCommand to fill a DataSet Uses other command objects to transmit changes back to the data source

13. 13 The DataSet In-memory copy of data No connection to a database. No knowledge of source or destination of that data that it contains. Simple form of relational database Has a collection of tables Has a collection of DataRelations

14. 14 The DataSet From ADO.NET 2.0 Step by Step

15. 15 The DataSet The DataTable Columns Like the column defintions from a SQL CREATE TABLE statement Name, Data Type, Max Length, Allows Nulls Rows The data Constraints Foreign Key Unique

16. 16 The DataSet Data Relation Programmatic interface for navigating from a master row in one table to related rows in another. Example: Order ID in an Invoice to matching Order IDs in all Line Items for that invoice. Does not enforce referential integrity A foreign key constraint does that.

17. 17 The DataSet A DataSet object can exist independently of any database. We will only use DataSets to hold data retrieved from a database.

18. 18 Summary DataAdapter Command DataReader Connection DataSet DATABASEDATABASE CLIENTCLIENT Data Provider ADO.NET