1. Accessing Databases using Ado.net
By Eric Vinokur

2. What we’re gonna do
Be introduced to technologies used for accessing databases
Become familiar with some ADO.NET classes
Look at what a database really is
Understand how to use and manipulate data from databases
Be introduced to SQL Query Statements

3. What is a database?
Location in a software that harbors large amounts of data
Information based
Physical Representation:
Collections of files with locations
Logical Representation:
Records, fields, or tables
Software is needed to view databases in this way

4. How to access a database
Client
Data Providers:
Microsoft Access
Microsoft SQL Server
Oracle
Open/Embedded Databases
Each provider must provide details for the methods that are used in the interface
ODBC and DBMS
Open Database Connectivity
Database Management System

5. SQl server

6. oracle

7. Oracle

8. SQL – Structured query language
SEQUEL
Designed by IBM in 1974
Standardized language used for requesting and manipulating data
SQL Statements or Queries– SELECT, INSERT, UPDATE, and DELETE data in database tables

9. Select Query
Select * From memberTable Order By LastName Asc, FirstName Asc;
Asterisk (*) selects all fields (columns) in database
Can replace * by field name(s)
Asc (ascending) returns in ascending order by LastName; duplicate last names ordered by first name
Retrieves all rows (records)
Where clause can be added to selectively identify rows
Select PhoneNumber From memberTable Where FirstName = 'Gary' AND LastName = 'Jones';

10. Sql statement – SQL Server

11. Sql statement – Oracle

12. ADO.Net ActiveX Direct Objects Addition to .NET Framework
Contains number of classes that can be used to retrieve, manipulate, and update data in databases.
Already exists in Visual Studio
Works in Disconnect (temp file) or Connect manner

13. Main classes of ado.net
Connection
Command
DataReader
DataAdapter

15. Using the classes

17. Possible implementations
Close( )
BeginDbTransaction( )
ChangeDatabase( )
CreateDbCommand( )
OpenStateChange( )

18. Datareader implementations

19. Connection Add using directive
using System.Data.OleDb;
Instantiate an object of connection class
Send connection string that includes the actual database provider and the data source (name of the database)
string sConnection;
sConnection = "Provider=Microsoft.Jet.OLEDB.4.0;" +
"Data Source=member.mdb";
OleDbConnection dbConn;
dbConn = new OleDbConnection(sConnection);
dbConn.Open();

20. Retrieving data with SQL
string sql;
sql = "Select * From memberTable Order By LastName Asc, "
+ "FirstName Asc;"; // Note the two semicolons
OleDbCommand dbCmd = new OleDbCommand();
dbCmd.CommandText = sql; // set command SQL string
dbCmd.Connection = dbConn; // dbConn is connection object

21. Retrieving data – continued
First call to dbReader.Read( ) retrieves first row
dbReader[0] refers to 1234
dbReader[1] refers to “Rebecca”
dbReader["FirstName"] also refers to "Rebecca"

22. Retrieving data – continued
Member aMember;
OleDbDataReader dbReader;
dbReader = dbCmd.ExecuteReader( ); // dbCmd—OleDbCommand object
while (dbReader.Read( ))
{ // retrieve records 1-by-1...
aMember = new Member(dbReader["FirstName"].ToString( ),
dbReader["LastName"].ToString( ));
this.listBox1.Items.Add(aMember); }
dbReader.Close(); // Close the Reader object
dbConn.Close(); // Close the Connection object

23. Assignments are hand-written or typed in word

24. Thank you
Except Nolter