1. Developing Database Applications Using ADO.NET and XML
Objectives
In this session, you will learn to:
Working in a connected environment
Ver. 1.0 Session 5 Slide 1 of 15

2. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters
A data adapter is integral to the working of ADO.NET
because data is transferred to and from a database through
a data adapter.
A data adapter retrieves data from a database into a
dataset.
The data adapter first compares the data in the dataset with
that in the database and then updates the database.
Data from a database can be accessed by configuring a
data adapter.
Ver. 1.0 Session 5 Slide 2 of 15

3. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
Following are the data adapters that can be configured to
connect to a database:
 SqlDataAdapter Accesses data specifically from
Microsoft SQL Server
 OleDbDataAdapter Accesses data from a database that is
supported by an OLE DB data provider
 OdbcDataAdapter Accesses data from a database that is
supported by an ODBC data provider
 OracleDataAdapter Accesses data from a database that is
supported by an Oracle data provider
Ver. 1.0 Session 5 Slide 3 of 15

4. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
The following properties and methods of a data adapter can
be used to perform various operations on a database:
 SelectCommand Refers to a DML statement or a stored procedure
to retrieve data from a database
 InsertCommand Refers to a data command to insert data into a
database
 UpdateCommand Refers to a data command to update a database
 DeleteCommand Refers to a data command to delete data from a
database
 Fill() Fills the dataset with the records from a database
 Update() Executes the corresponding Insert, Update, or
Delete commands for each inserted, modified,
or deleted row to reflect the changes in a
database
Ver. 1.0 Session 5 Slide 4 of 15

5. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
• Consider the following code snippet of creating a
DataAdapter object and using the SelectCommand
property of the object:
SqlConnection cn = new
SqlConnection();
cn.ConnectionString = "Data Set a connection string
source=SQLSERVER01;Initial
catalog=HR;User id=sa;
Password=niit#1234";
DataSet DataSet1 = new DataSet();Creating a DataSet object
SqlDataAdapter da = new Creating a SqlDataAdapter
SqlDataAdapter(); object
SqlCommand cmd=new SqlCommand Passing the SQL query to the
("Select * from Employees", cn); command object.
da.SelectCommand = cmd; Retrieving records from the
Filling the dataset
Employees table with records
da.Fill(DataSet1); from the Employees table
Ver. 1.0 Session 5 Slide 5 of 15

6. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
• A data adapter handles data transfer between the database
and the dataset through its properties and methods, and
displays data through the process of table mapping.
• After a dataset has been created, the data adapter uses the
process of table mapping to map the columns in the
database table with the dataset columns.
• A data adapter uses the TableMappings property, a
collection of DatatableMapping objects that is used for
mapping between the database table and the DataTable
object in the dataset.
Ver. 1.0 Session 5 Slide 6 of 15

7. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
A major challenge related to data access is that more than
one user might need to simultaneously access data in a
database.
Another challenge is more than one user might need to
access the data anytime, anywhere. This challenge can be
overcome by implementing database locking while a
transaction is executing.
However, if database locking is not implemented, it can lead
to data concurrency conflicts that arise from multiple
updates being performed on the database.
Ver. 1.0 Session 5 Slide 7 of 15

8. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
Resolving data concurrency conflicts is a business decision,
with the following choices:
Prioritized on time; first update wins
Prioritized on time; last update wins
Prioritized on role
Prioritized on location
User resolves the conflict
Ver. 1.0 Session 5 Slide 8 of 15

9. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
A significant way to increase the performance of data
updates is to update and send the changes to the database
in batches. This is known as batch updates.
Batch updates are performed by using the
UpdateBatchSize property of the SqlDataAdapter
object.
By default, the UpdateBatchSize property is set to 1.
One way to confirm that the changes are being sent to the
database server in batches is to add a RowUpdated event
to the SqlDataAdapter object. This event will show the
number of rows affected in the last batch.
Ver. 1.0 Session 5 Slide 9 of 15

10. Developing Database Applications Using ADO.NET and XML
Working with Data Adapters (Contd.)
• ADO.NET provides support for classes that can create any
provider-specific objects. These classes are known as the
DbProviderFactories classes.
• The DbProviderFactories class contains a method
called GetFactoryClasses that returns a data table,
which is populated with data from various providers, as
shown in the following figure.
Ver. 1.0 Session 5 Slide 10 of 15

11. Developing Database Applications Using ADO.NET and XML
Just a minute
_______ class can create any data provider-specific object.
1. DbCommand
2. DbProviderFactories
3. DbParameter
4. DbConnection
Answer:
2. DbProviderFactories
Ver. 1.0 Session 5 Slide 11 of 15

12. Developing Database Applications Using ADO.NET and XML
Demo: Manipulating Data in a Connected Environment
Problem Statement:
The HR Manager of Tebisco needs to update the number of
vacancies, for those positions where the number of vacancies
is not more than 10. This updation will be based on the current
position code of employees.
As a part of the development team, you need to execute two
queries, one to retrieve the number of vacancies per position
code, and the other to update the number of vacancies on the
basis of the current position code of employees.
You need to develop an application that can execute both
queries on a single database connection.
Hint: You need to access the InternalJobPosting and
Employee tables of the HR database.
Ver. 1.0 Session 5 Slide 12 of 15

13. Developing Database Applications Using ADO.NET and XML
Summary
In this session, you learned that:
 A data adapter, which is a part of the connected environment,
retrieves data from a database into a dataset.
 The data adapters that can be configured to connect to a
database in Visual Studio .NET are:
SqlDataAdapter
OleDbDataAdapter
OdbcDataAdapter
OracleDataAdapter
Ver. 1.0 Session 5 Slide 13 of 15

14. Developing Database Applications Using ADO.NET and XML
Summary (Contd.)
The following properties and methods of a data adapter can be
used to perform the various operations on a database:
 SelectCommand
 InsertCommand
 UpdateCommand
 DeleteCommand
 Fill()
 Update()
 A data adapter handles data transfer between the database
and the dataset through its properties and methods, and
displays the data through the process of table mapping.
Ver. 1.0 Session 5 Slide 14 of 15

15. Developing Database Applications Using ADO.NET and XML
Summary (Contd.)
Resolving data concurrency conflicts is a business decision,
with the following choices:
 Prioritized on time; first update wins
 Prioritized on time; last update wins
 Prioritized on role
 Prioritized on location
 User resolves the conflict
 A significant way to increase the performance of data updates
is to update and send the changes to the database in batches.
This is known as batch updates.
 ADO.NET provides support for classes that can create any
provider-specific objects, such as SqlClient, Odbc,
OracleClient, and OleDb. These classes are known as
DbProviderFactories classes.
Ver. 1.0 Session 5 Slide 15 of 15