ddcauado.net session01

7/30/2019 Ddcauado.net Session01

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Developing Data-Centric Applications Using ADO.NET

Session 1

Business applications need to manage voluminous data.Data is generally stored in a relational database in the formof related tables or is stored in text format in XMLdocuments. Most business applications allow users toretrieve the data stored in a database and present it in auser-friendly interface without writing the databasecommands. ADO.NET is a model used by .NET applicationsto communicate with a database for retrieving, accessing,and updating data. This module will provide the necessaryskills to the students to work as a database application

developer in the industry.

Rationale


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Session 1

A student registering for this module should be able toperform the following tasks:

Work with XML

Work with SQL queries

Prerequisites


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Session 1

Brief History:

Tebisco is a leading producer and distributor of snacks in theU.S., as well as in most of the companys 23 internationalmarkets. In 1998, consumers spent $9.2 billion on Tebiscossnacks, $1.4 billion more than in the previous year.

Tebisco started as a small bakery in Round Rock, Texas in1978. In a short time, its gingersnaps, macaroons, shortbreadand other cookies were popular all over the U.S. Three yearsago, the management embarked on a rapid expansion plan.They set up offices in Asia and Europe, in addition to

strengthening their U.S. operations.Tebisco has got a centralized database management systemwhereby the information about all the HR activities ismaintained.

Case Study - Tebisco


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Session 1

In this session, you will learn to:

Understand the ADO.NET object model

Create and manage connections

Objectives


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Session 1

Business applications allow users to retrieve data from adatabase by presenting data in a user-friendly interface.

User need not remember the database commands forretrieving or updating data in the database.

Microsoft has created a family of data access technologiesto help programmers build efficient applications to accessdata, regardless of its source.

The guidelines that can be followed for selecting anappropriate data access technology are:

Understanding ADO.NET

Use ADO.NET for writing a managed codetargeting the .NET Framework in Visual Basic,C#, and C++.

Use Microsoft ODBC for writing a native codetargeting Windows by using C or C++.Use (OLE) DB for writing a Microsoftbased application, a VB 6 COM application, ora C++ application using COM.

Use JDBC for writing a Java code targetingSQL Server.


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Session 1

ADO.NET is a part of the .NET Framework architecture.

Understanding ADO.NET (Contd.)


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Session 1

ADO.NET is based on an object model that is based on thestandards laid down by W3C.

The following figure shows the ADO.NET object model.

The ADO.NET Object Model




Session 1

The two key components of ADO.NET Object model are:

Data provider

Dataset

The ADO.NET Object Model (Contd.)

Is required for:

Connecting to a database.

Retrieving data.

Storing the data in a dataset.

Reading the retrieved data.

Updating the database.

Has four key components:

Connection

Command

DataReader

DataAdapter




Session 1

The two key components of ADO.NET Object model are:

Data provider

Dataset

The ADO.NET Object Model (Contd.)

Is a disconnected, cached set ofrecords that are retrieved from adatabase.

Is present in the Dataset class inthe System.Data namespace.

Has the following keycomponents:

DataTableCollection

DataRelationCollection

DataTable

DataRowCollection

DataColoumnCollection


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Session 1

Which of the following components of a data provider isused to retrieve, insert, delete, or modify data in a datasource?

1. Connection

2. Command

3. DataReader

4. DataAdapter

Just a minute

Answer:

2. Command


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Session 1

The key features of ADO.NET are:

Disconnected data architecture

Data cached in datasets

Scalability

Data transfer in XML format

Features of ADO.NET

Applications connect tothe database only whileretrieving and updatingdata.

Connection with thedatabase is closed,once the data isretrieved.

Connection is

re-established whenthe data needs to beupdated.

The data is retrievedand stored in datasets.

You can work with therecords stored in adataset as you workwith real data.

The dataset isindependent of data

source and you remaindisconnected from thedata source.

Database operationsare performed on thedataset instead of onthe database.

As a result, resourcesare saved and thedatabase can meet the

increasing demands ofusers more efficiently.

XML is the fundamentalformat for data transferin ADO.NET.

Because a dataset isstored in the XMLformat, you can

transmit it betweendifferent types ofapplications.


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Session 1

To create and manage connections, you need to:

Create a connection object.

Create a command object.

Open the connection object.

Execute the SQL statement in the command object.Close the connection object.

Creating and Managing Connections


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Session 1

SqlConnection connection =

new SqlConnection();

connection.ConnectionString =

"Data Source=SQLSERVER01;

Initial Catalog=HR;

User ID=sa;

Password=password";

Create a SqlConnection object.

SqlConnection class is used to

connect to a SQL Server.The ConnectionStringproperty

provides information, such as thedata source and database name,that is used to establish aconnection with a database.

Name of the Server to be usedwhen a connection is open.Name of the database.

Used to specify the Server loginaccount.Login password for the Serveraccount.

Creating a Connection Object

Execute the following steps to create a connection to thedatabase:


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Session 1

Which of the following parameters of ConnectionString isused to specify the name of the database?

1. Provider

2. Initial Catalog

3. Data source4. Database

Just a minute

Answer:

2. Initial Catalog


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Session 1

SqlCommand cmd = new

SqlCommand

(SELECT * FROM

monthlysalary,connection);

Creating a Command Object

To execute an SQL statement, you need to

create an instance of the SqlCommand

class.The two parameters that are passed to the

SqlCommnad object are, the SQL query tobe executed and the SqlConnection

object.

Execute the following steps to create a command object:


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Session 1

//SqlConnection connection

connection.Open();

Opening the Connection Object

It opens a database connectionwith the property settingsspecified by the

ConnectionString property.

Execute the following steps to open a connection:


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Session 1

To execute the query passed in the Command object, youcan call one of the following methods:

Executing SQL Statements in the Command Object

// Creating a SqlConnection object

SqlConnection connection = new

SqlConnection();

// Creates a connection string to the HRdatabase

connection.ConnectionString = "Data Source=

SQLSERVER01; Initial Catalog=HR; User

ID=sa; Password=niit#1234";

connection.Open();

// Creating a SqlCommand object

SqlCommand cmd = new SqlCommand("select *

from monthlysalary", connection);

// Creating SqlReader object

SqlDataReader myReader =

cmd.ExecuteReader();


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Session 1

//SqlConnection connection

connection.Close();

Closing the Connection Object

It closes the connection to thedatabase.

Execute the following steps toclose a connection:


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Handling Connection Events:

The two key events for the SqlConnection class are:

StateChange event

InfoMessage event

Closing the Connection Object (Contd.)

This event occurs when the stateof the connection changes.

It receives an argument of type

StateChangeEventArgs.StateChangeEventArgs has the

following properties:CurrentState

OriginalState

This event occurs when aninformational message or

warning is returned from a datasource.

It receives an argument of typeSqlInfoMessageEventArgs.

SqlInfoMessageEventArgs

has the following properties:

Errors

Message

Source


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Session 1

Connection pooling enables a data source to reuseconnections for a particular user.

Connection pooling is controlled by certain parameters thatare placed into the connection string.

Connectiontimeout

Min poolsize

Max poolsize

Pooling

Connectionreset

Loadbalancingtimeout,connectionlifetime

Enlist

Implementing Connection Pooling

It is the time in seconds to waitwhile a connection to the datasource is attempted. Thedefault value is 15 seconds.

It is used to mention theminimum number ofconnections maintained in thepool. The default value is 0.

It is used to mention themaximum number ofconnections allowed in the pool.The default value is 100.

When true, it causes therequest for a new connection tobe drawn from the pool.It indicates that the databaseconnection will be reset when

the connection is removed from

the pool.It specifies the maximum timein seconds that a pooledconnection should live.

When the value is true, theconnection is automatically enlistedinto the creation threads current

transaction context.


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A request for a connection ismade by the application usingthe Open() method.

If the Pooling property is set

to true, the pooler attempts toacquire a connection from thepool otherwise a newconnection is created.

Close the connection bycalling the close() method.

Implementing Connection Pooling (Contd.)


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Session 1

Problem Statement:

Tebisco is a leading producer and distributor of snacks in theUnited States. It is planning to start its annual appraisalprocess. Before starting up with the appraisal process, thesenior management requires a list of all employees. The

details include employee name, employee code, currentposition, designation, and joining date.

As a member of the development team, you have been askedto develop an application that will display the employee details.

Hint: You need to refer to the Employee table of the HRdatabase.

Demo: Retrieving Data From a SQL Database


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Session 1

In this session, you learned that:

ADO.NET is a data access programming model for accessingthe data stored in a database from a .NET application.

The ADO.NET object model consists of two main components,data provider and dataset.

A data provider is used for connecting to a database, retrievingdata, storing the data in a dataset, reading the retrieved data,and updating the database.

The various types of data providers are:

.NET Framework data provider for SQL Server

.NET Framework data provider for OLEDB

.NET Framework data provider for ODBC

.NET Framework data provider for Oracle

Summary


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Session 1

The four key components of a data provider are:

Connection

Commnd

DataReader

DataAdapter

The dataset is memory-based relational representation of data.The main features of ADO.NET are:

Disconnected data architecture

Data cached in datasets

Scalability

Data transfer in XML format

Summary (Contd.)


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In order to create and manage connection to the database, youneed to perform the following steps:

1. Create a connection object.

2. Create a command object.

3. Open the connection object.

4. Execute the SQL statement in the command object.5. Close the connection object.

The two key events for the SqlConnection class are:

StateChange event

InfoMessage event

Connection pooling enables a data source to reuseconnections for a particular user.

Summary (Contd.)

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