1. ADO
ActiveX Data Object

2. ActiveX Data Object
• ADO is ActiveX Data Object that allows you to use data
from databases without knowing the implementation of
such a database.
• To access the data, programmer even don't have to
know SQL although there is a possibility of using SQL
commands through ADO as well.
• One of the main objects in ADO is a Recordset.
• The general idea of using ADO is the following:
– firstly you have to create and open a connection object that
allows you to connect to the database.
– Then you create a Recordset and retrieve data from the
database to it.
– Afterwards you have the possibility to save potential changes to
the database.

3. ActiveX Data Object
• ADO.NET is ActiveX Data Object for .NET and
it's a successor to ADO.NET although it was
changed completely.
• Its functionalities are similar to the ones from
ADO.
• It allows you to connect to data sources and
perform some operations on them.
• The main object in ADO.NET is Dataset, it's a
bit similar to Recordset but it provides more
possibilities for developers.
• ADO.NET makes possible disconnected
access to data by taking advantage of XML
files.

4. ActiveX Data Object
• ADO.NET provides also frameworks that make
using databases even simpler.
• ADO.NET Entity Framework for object-relational
mapping.
• It presents data from databases as objects and
thus makes it much easier to use it by rising
level of abstraction.
• Another framework that is very useful is LINQ
(Language Integrated Query), which allow you to
query data in a unified and clear way.

5. ADO and ADO.NET
• The ADO Recordset is now called the ADO.NET DataSet.
• ADO.NET uses disconnected models based on messages
whereas ADO is rather connection oriented.
• ADO.NET supports XML in an easy and clear way,
moreover it uses XML for passing data. On the other hand
standard ADO uses binary representation for passing
data.
• ADO is based on COM (Component Object Model) and
ADO.NET uses CLR (Common Language Runtime).
• Recordset in ADO and DataSet in ADO.NET.
• ADO.NET uses XML to communicate DataSets from point
to point.
• DataSets are a disconnected form of data access.

6. DataSet and Recordset
• Recordset represents data in memory, usually it's a table
or result of a query such as joining two tables or using
where clause.
• At one time there can be only one current record in
Recordset, if you want to perform operations on other
record you have to use move method.
• On the other hand DataSet can contain one or more tables
from database, these tables are stored in object called
DataTable.
• It is also very easy to retrieve data from it, you can use
simple foreach loop to do so.
• With DataSet you can also maintain relationships between
data tables such as for instance foreign key. Generally
DataSet can include more rich and complex data and
organize it in a clear manner.

7. DataSet and Recordset
• As I mentioned before ADO Recordset requires
constant connection to database to perform
some operations on it while ADO.NET DataSet
allows you to make changes and submit all of
them to the database later.
• ADO.NET uses also data adapter which
communicates with OLE DB provider while in
ADO you communicate with it directly.
• Data adapters are significant advantage
because it's very easy to set up and manage this
connection.

8. DataSet and Recordset
• performance of DataSets is better because of
its architecture, it's faster and more portable
than Recordset.
• DataSet stores data in XML so it's easier to
transfer it to other applications and they are
more firewall-prove than Recordsets that are
transferred using COM marshalling.
• DataSet is better and more robust tool to
manage data from databases and it provides
more functionalities.

9. DataSet
string source = “server=(local)” +“integrated
security=SSPI;” +“database=Northwind”;
SqlConnection conn = new SqlConnection(source);
conn.Open();
string query = "SELECT id, name FROM employees";
SqlDataAdapter adapter = new SqlDataAdapter(query, conn);
DataSet company = new DataSet();
adapter.Fill(company, "employees");
foreach (DataRow employee in company.Tables["employees"].Rows)
{
Console.WriteLine(employee["id"] + " " + employee["name"]);
}

10. Namespaces
• System.Data—All generic data access classes.
• System.Data.Common—Classes shared (or
overridden) by individual data providers.
• System.Data.Odbc—ODBC provider classes.
• System.Data.OleDb—OLE DB provider classes.
• System.Data.Oracle—Oracle provider classes.
• System.Data.SqlClient—SQLServer provider
classes.
• System.Data.SqlTypes—SQLServer data types.

11. classes are contained in the
System.Data
• DataSet—This object is designed for disconnected use
and can contain a set of DataTables and include
relationships between these tables.
• DataTable—A container of data that consists of one or
more DataColumns and, when populated, will have one
or more DataRows containing data.
• DataRow—A number of values, akin to a row from a
database table, or a row from a spreadsheet.
• DataColumn—This object contains the definition of a
column, such as the name and data type.

12. Database-Specific Classes
• SqlCommand, OleDbCommand, OracleCommand, and
ODBCComm and—Used as wrappers(binds) for SQL
statements or stored procedure calls.
• SqlConnection, OleDbConnection, OracleConnection,
ODBCConnection—Used to connect to the database.
Similar to an ADO Connection.
• SqlDataAdapter, OleDbDataAdapter,
OracleDataAdapter, ODBCDataAdapter—Used to hold
select, insert, update, and delete commands, which
are then used to populate a DataSet and update the
Database.
• SqlDataReader, OleDbDataReader, OracleDataReader,
ODBCDataReader —Used as a forward only,
connected data reader.
• dr = cmd.ExecuteReader();
while (dr.Read())

13. Executing Commands
• ExecuteNonQuery()—Executes the command
but does not return any output.
– SqlCommand cmd = new SqlCommand(select, conn);
– int rowsReturned = cmd.ExecuteNonQuery();
– Console.WriteLine(“{0} rows returned.”, rowsReturned);
• ExecuteReader()—Executes the command and
returns a typed DataReader.
–
–
–
dr = cmd.ExecuteReader();
while (dr.Read())
{
textBox1.Text = dr[0].ToString();
• ExecuteScalar()—Executes the command and
returns a single value.
– string select = “SELECT COUNT(*) FROM Customers”;
– object o = cmd.ExecuteScalar();
– Console.WriteLine ( o ) ;

15. Connecting to a User Instance
• The UserInstance and AttachDBFilenameConnectionS
tring keywords allow a SqlConnection to connect to a
user instance. User instances are also supported by
the SqlConnectionStringBuilderUserInstance and Attac
hDBFilename properties.
• Note the following about the sample connection string
shown below:
• The Data Source keyword refers to the parent instance
of SQL Server Express that is generating the user
instance. The default instance is .sqlexpress.

16. • Integrated Security is set to true. To
connect to a user instance, Windows
Authentication is required; SQL Server
logins are not supported.
• The User Instance is set to true, which
invokes a user instance.

17. • The AttachDbFileName connection string keyword is
used to attach the primary database file (.mdf), which
must include the full path
name. AttachDbFileName also corresponds to the
"extended properties" and "initial file name" keys within
a SqlConnection connection string.
• The |DataDirectory| substitution string enclosed in the
pipe symbols refers to the data directory of the
application opening the connection and provides a
relative path indicating the location of the .mdf and .ldf
database and log files. If you want to locate these files
elsewhere, you must provide the full path to the files.

18. The Security Support Provider
Interface
• To connect to the database server is recommended
to use Windows Authentication, commonly known as
integrated security. To specify the Windows
authentication, you can use any of the following two
key-value pairs with the data provider. NET
Framework for SQL Server:
• Integrated Security = true;
• Integrated Security = SSPI;
• However, only the second works with the data
provider. NET Framework OleDb. If you set
Integrated Security = true for ConnectionString an
exception is thrown.

19. • To specify the Windows authentication in
the data provider. NET Framework for
ODBC, you should use the following keyvalue pair.
• Trusted_Connection = yes;
• Let me start with Integrated Security =
false
• false User ID and Password are specified
in the connection string.
true Windows account credentials are
used for authentication.

20. • Recognized values are true, false, yes, no,
and SSPI.
• If User ID and Password are specified and
Integrated Security is set to true,
then User ID andPassword will be ignored
and Integrated Security will be used

21. SQL Server Express User
Instances
• Microsoft SQL Server Express Edition (SQL
Server Express) supports the user instance
feature, which is only available when using
the .NET Framework Data Provider for SQL
Server (SqlClient). A user instance is a
separate instance of the SQL Server Express
Database Engine that is generated by a parent
instance. User instances allow users who are
not administrators on their local computers to
attach and connect to SQL Server Express
databases. Each instance runs under the
security context of the individual user, on a one-