1. Introduction to Database Processing with ADO.NET

2. The ASP.NET / ADO.NET Conundrum
The tools and wizards are wonderful for simple applications
As applications become more complex and “real”
You need to write code between the controls and the data providers
Nested controls and one-to-many views become complex
At some point, the visual designers become useless

3. Lecture Overview Introduce ASP.NET data sources
Introduce the ASP.NET data bound controls
Show a few SIMPLE examples to get us started

4. History of ADO (1)
Open Database Connectivity (ODBC) was created to provide a uniform API to access SQL database servers
OLE DB evolved from ODBC and provided a COM based interface
Next came the first versions of ADO, which encapsulated OLE DB
ADO.NET is the current generation of ADO and uses .NET Managed Providers

5. History of ADO (2)
While not a problem Microsoft has stepped away from all MSAccess support.
The data controls are gone
Necessary Jet versions are not usually installed
So we will use SQLServer in this course

6. ADO / ASP.NET NOTE The capabilities of ASP and ADO are vast
There are many ways to accomplish the same task
DataReaders vs. DataAdapters
DataSource controls vs. manual binding
Bound control configuration is sophisticated

7. ADO.NET -The Role of Managed Providers
Managed providers interact with a data source and return data to an application
Data sources are typically (almost always) disconnected
After data is returned to the application, connections are closed

8. ADO.NET Namespaces / Classes (Intro)
There are many of these
Some you don’t need to work with directly
There are many ways to accomplish the same task
Mastery of the topic requires that you understand what the controls do and how they interact with the underlying classes

9. ADO.NET Namespaces (1) Here’s the fabric System.Data
System.Data.SqlClient
System.Data.OleDb
System.Data.SqlTypes

10. ADO.NET Classes (1)
Connection – creates the connection with the data source (database)
Support is provided for ORACLE, SQL Server, Access, etc.
Transaction – allows for transactional processing
Command – typically an SQL statement executed against a database server
Could be a stored procedure
Parameter – a parameter passed to a command

11. ADO.NET Classes (2)
DataAdapter – a database object that returns a disconnected set of records (DataSet and DataTable)
DataReader – a forward-only reader to get database records

12. Introduction to Connections
Executing a database command is generally a two-step process
Create a connection
Prepare and execute a command
The ASP.NET controls help automate much of the process
There are specific connection classes for OLE DB, SQL Server and others
They all work the same way

13. Connection Strings
There are tools to build these for you based on the database provider
Connection strings are typically stored in the web.config file
They store all information needed to establish a database connection
More later

14. Connection Strings (Example)
Connection strings are usually stored in web.config
The following reads the connection string from web.config

15. Connection Strings (Example)
The SqlConnection object represents the connection itself. It’s properties depict the connection status

16. Executing Commands (Introduction)
Use the SqlCommand object to
Return one record one field (ExecuteNonQuery)
Execute SQL INSERT, UPDATE, DELETE statements
Return records in the form of a DataTable
Return records one row at a time (DataReader)

17. SqlCommand Object (Using 1 row)
The OleDbCommand or SqlCommand objects work the same way
Set the CommandText property to the SQL statement to execute
Set the CommandType property to CommandType.Text
Set the Connection property to an existing Connection object

18. SqlCommand Object (Using 1 row)
To return one field from one row, call ExecutScalar() on the SqlCommand object

19. SqlCommand Object (Returning Nothing)
Use the ExecuteNonQuery method to execute SQL statements that do not return values
INSERT / UPDATE / DELETE
As before, the CommandText property stores the SQL statement
Two ways to do INSERT / UPDATE /DELETE
With parameters
Roll the statement by hand

20. SqlCommand Object (Returning Nothing - Manual)
Use create the CommandText, CommandType and Connection as before
The INSERT / UPDATE / DELETE statements get contorted

21. SqlCommand Object (Parameters 1 )
Parameters provide the preferred way to pass data to INSERT / UPDATE / DELETE and other SQL statements
Parameters begin with in the SQL statement

22. SqlCommand Object (Parameters 1 )
Then we create the parameters as part of the command object
We are adding items to the parameters collection

23. Using the DataReader This is straight out of the book
There are much better ways to read data but here is the first cut
It’s a forward only reader
Call Read to read the first and subsequent records
Create an SqlCommand object as before
Call ExecuteReader to initialize
Call Read to read each record
Index contains the field name

24. Using the DataReader (example)

25. Reading Multiple Records
Here, we use the DataSet and DataTable objects along with the DataAdapter
Steps
Create SqlCommand with the SELECT statement as before
Create a new SqlDataAdapter
Create a DataSet
Call Fill on the DataAdapter to populate the DataSet

26. Reading Multiple Records

27. Introduction to Data Sources
Data sources establish the connection between an ASP.NET application and a database
These are not the same controls as the desktop controls

28. Data Source Controls (Categories)
Tabular
AccessDataSource – For Access databases
SqlDataSource – For SQL databases
ObjectDataSource – For custom business objects
Hierarchical
SiteMapDataSource – For menus
XmlDataSource – To bind XML documents

29. Data Sources (Core Concepts)
The ASP.NET data source controls are bound to a page rather than the application
They belong to System.Web rather than System.Data so they are again unique to ASP.NET
Underneath the hood, there is a DataSet
You can use the System.Data classes from an ASP.NET application
Visual Studio does a great job configuring the data source controls

30. Data Sources (Under the Hood 1)
The Wizards configure properties to
Write SELECT statements and customize them
Write INSERT, UPDATE, and DELETE statements that are executed by other bound controls

31. Data Sources (Under the Hood 2)
The Properties window tells the tale