UNIT – 5

INBUILT FUNCTIONS AND

DATABASE ACCESS USING

ADO.NET

SYLLABUS

5.1 Inbuilt Functions : Mathematical Functions( The Abs

function, The Exp function ,The Fix Function , The Int

Function, The Log Function , The Rnd( ) Function, The

Round Function, The Sqrt Function),

5.2 String manipulation( The Mid Function , The Right

Function, The Left Function , The Trim Function, The

Ltrim Function , The Rtrim Function , The InStr function

, The Ucase and the Lcase Functions , The Chr and the

Asc functions, Formatting Functions), Format Functions

( Formatting Using ToString Method ,Formatting Date and

Time ) 2

5.3 ADO .NET Object Model: Dataprovider( connection,

command, data reader, data adapter, datareaders)

Dataset (datatablecollection(datatable, datarows,

datacolumns, data constraints), datarelationcollection)

5.4 ADO .NET Programming :Creating a Database

Application, Creating Connection to a Database using

ADO.NET , Populating Data in ADO.NET, Browsing

Records, Datagrid view, Editing, Saving, Adding and

Deleting Records using bounded and unbounded

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5.1 INBUILT FUNCTIONS

There are there types of inbuilt function in

VB.NET.

1) Mathematical Functions

2) String Manipulation Functions

3) Formatting Functions

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1. MATHEMATICAL FUNCTIONS

All the Math functions of VB have been replaced

by the methods of the Math class.

1) Abs Function

This method returns the absolute value of its argument.

Syntax: Math. Abs (number)

Example: Math.Abs(-8)

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2) Exp function The Exp of a number x is the exponential value of x,

i.e. ex .

Syntax: Math.Exp (number)

3) Fix Function

The Fix function truncate the decimal part of a positive

number and returns the largest integer but if

negative number give it returns smaller than the

number.

Syntax: Fix(Number)

Example: Fix(9.7)

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4) Int Function

The Int is a function that converts a number into an

integer by truncating its decimal part.

Syntax: Int(Number)

Example: Int(2.4

5) Log Function

The Log function is the function that returns the natural

logarithm of a number.

Syntax: Math.Log (Number)

Example: Math.Log(10)

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6) Rnd( ) Function

The Rnd function returns a random value between

0 and 1.

Syntax: Rnd(Number)

Number is an optional argument

7) Round Function

The Round function is the function that rounds up a

number to a certain number of decimal places.

Syntax: Math.Round(Number)

Example: Math.Round (7.2567, 2)8

8) Sqrt Function

The Sqrt function is the function that takes the

square root of a number.

Syntax: Math.Sqrt (number)

Example: Math. Sqrt(49)

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5.2. STRING MANIPULATION FUNCTIONS

1) Mid(string, start, [length]) Function

The Mid() function returns a section of a string of

length characters, starting at position start.

Syntax: Mid(string, start, [length])

Example: Mid(“Good Morning”,1,4)

2) Right(string, number) Function

This function returns a number of characters from

the right side of a string.

Syntax: Right(string, number)

Example: Right(“Morning”,1)

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3) Left(string, number)Function

This function returns a number of characters

from the left side(beginning) of a string.

Syntax: Left(string, number)

Example: Left(“Morning”,1)

4) Trim(“String”)Function

The Ttrim function trims the empty spaces on both side

of the string .It remove empty space both side.

Syntax: Trim(“String”)

Example: Trim (“ Visual Basic.net ”) 11

5) LTrim(“String”) Function

The Ltrim function trims the remove empty spaces of

the left portion of the String.

Syntax : Ltrim(“String”)

Example: Ltrim (“ Visual Basic.net”)

6) RTrim(“String”) Function

The Rtrim function trims the remove empty spaces of

the right portion of the String.

Syntax: Rtrim(“String”)

Example: Rtrim (“ Visual Basic.net ”)

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7) InStr Function

This function searches one string into another string

and returns the starting position of the first

occurrence of a search string.

Syntax: InStr([start,],string1,string2,[compare])

Example: InStr(1,”Good Night”,

”Good”,CompareMethod.Text)

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8) Ucase Function This function accepts a string or character as an

argument and returns a string or character converted

into upper case.

Syntax : UCase(“String” or Character)

Example: UCase(“vpmp”)

9) Lcase Function This function accepts a string or character as an

argument and returns a string or character converted

into lowercase.

Syntax : LCase(“String” or Character)

Example: LCase(“VPMP”)14

9) Chr Function This function returns a character corresponds to the

ASCII value specified as an argument.

Syntax : Chr(char code)

Example: Chr(65)

10) Asc Function

This function returns a ASCII value corresponds to

the given character.

Syntax : Asc(“character”)

Example: Asc(“A”)

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3. FORMATTING FUNCTION

1. Now() Function

This function returns both the system date and time. The statement

Syntax:

MsgBox(Now())

displays a date/time combination such as 9/13/1998 09:23:10 PM in a message box. To extract the date or time part of the value returned by the Now() function, use the Date and TimeOfDay

properties:

Console.WriteLine(Now.Date.ToString)

Console.WriteLine(Now.TimeOfDay.ToString)16

Formate Styles

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Formate Style Description

General Date Format the Current Date & Time

Long Date or D Display the Current Date in long format

Short Date or d Display the Current Date in Short format

Long Time or T Display the Current Time in long format

Short Time or t Display the Current Time in Short format

Example

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Example Output

Format(Date.Now,”Gener

al Date”)

28/3/2017 3:10 PM

Format(Date.Now, “D”) Monday , March 28 2017

Format(Date.Now, “d”) 28/3/2017

5.3 ADO.NET OBJECT MODEL

ADO.NET stands for Active X Data Object.

ADO.NET is an Object Oriented Set of Libraries

that allows to interact with Data Sources.& Data

Source is a Database.

ADO.NET provides data access services in the Microsoft

.NET platform.

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ADO.NET OBJECT MODEL /

ADO.NET ARCHITECTURE

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ADO.NET OBJECT MODEL

You can use ADO.NET to access data by using the new

.NET Framework data providers which are:

1. Data Provider for SQL Server

(System.Data.SqlClient).

2. Data Provider for OLEDB (System.Data.OleDb).

3. Data Provider for ODBC (System.Data.Odbc).

4. Data Provider for Oracle (System.Data.OracleClient).

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ADO.NET OBJECT MODEL

Architecture of ADO.net basically consist of

two Components

1) .NET Framework Data Provider

(connected objects)

2) DataSet

(disconnected Objects)

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1.1 CONNECTION OBJECT The Connection object Create the connection to the

database.

The ADO Connection Object is used to create an open connection to a data source. Through this connection, you can access and manipulate a database.

It is Two type of connection provide.

1. SqlConnection

2. OleDbConnection

Syntax of create connection object

1) Microsoft Access

Dim cn As New SqlConnection()

or

Dim cn As New OleDbConnection(“ConnectionString”)

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2) Microsoft SqlConnection

Syntax of create connection object

Dim cn As New SqlConnection()

or

Dim cn As New SqlConnection(“ConnectionString”)

Connection String

Connection string is a sequence of name and

value pair separated by semicolon.

Connection string is used to specify name of provider,

type of data source , its location , username, password

etc.24

EXAMPLE OF CONNECTION STRING

Dim cn As New SqlConnection()

cn.ConnectionString=

"DataSource=.\SQLEXPRESS;AttachDbFilename

=C:\Users\-\documents\visual studio

2010\Projects\WindowsApplication1\Windows

Application1\Database1.mdf;Integrated

Security=True;User Instance=True"

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PROPERTIES OF CONNECTION OBJECT

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METHODS OF CONNECTION OBJECT

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2. COMMAND OBJECT

The ADO Command object is used specify query to

perform with data source or database.

The query can perform actions like creating,

adding, retrieving, deleting or updating records.

If the query is used to retrieve data, the data will

be returned as a RecordSet object. This means that

the retrieved data can be manipulated by properties,

collections, methods, and events of the RecordSet object.

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.Net Provides Two Type of Command

Classes:

1. SqlCommand

2. Oledb Command

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COMMAND OBJECT

Syntax to create Command Object

1) For Microsoft Access

Dim cmd As New OleDbCommand()

Or

Dim cmd As New OleDbCommand(Query, connection)

2) For Sql Server

Dim cmd As New SqlCommand()

Or

Dim cmd As New SqlCommand(Query, connection)

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Example-1Dim cn As New SqlConnection

("DataSource=.\SQLEXPRESS;AttachDbFilename=C:\Users\-

\documents\visual studio

2010\Projects\WindowsApplication1\WindowsApplication1\Database

1.mdf;Integrated Security=True;User Instance=True“)

Dim cm As New SqlCommand()

cm.Connection = cn

cm.CommandText = “Select * from student;”

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3. DATA READER

DataReader provides a Read-only, Forward-only

stream of result from a database.

Data reader object is used to retrieve records from data

source and examine them one by one.

The important property of data reader are

1) Fast

2) Forward only

3) Read only

The SqlCommand.ExecuteReader() Method

returns a SqlDataReader Object.

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Create Data Reader Object

Syntax

Dim dr As OleDbDataReader()

or

Dim dr As SqlDataReader()

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4. DATA ADAPTER

A DataAdapter (DataAdapter class) is an object used to

exchange data between a data source and a data set.

In other words, a DataAdapter is used to read data from

a data source into a data set, as well as writing changed

data from the data set back to the data source.

A DataAdapter is used to fill a DataTable or DataSet

with data from the database with its Fill() Method.

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Properties of DataAdapter

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Properties Description

DeleteCommand Represents a DELETE Statement or deleted

records from the data Table

InsertCommand Represents a INSERT Statement or

inserting records from the data Table

SelectCommand Represents a SELECT Statement or select

records from the data Table

UpdateCommand Represents a UPDATE Statement or

Updating records from the data Table

TableMappings Represents a collection of mapping

between actual data source table & a Data

Table object.

Create Data Adapter Object

Syntax

Dim adp As sqlDataAdapter()

Create DataAdapter object by passing

parameter

Syntax

Dim adp as sqlDataAdapter(“query”,connection)

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Example-1Dim cn As New SqlConnection(“Connection String”)

Dim q1 As String = “ select * from student;”

Dim cm As New SqlCommand(q1,cn)

Dim da As New SqlDataAdapter(cm)

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DIFFERENCES BETWEEN DATA ADAPTER &

DATA READER

Data Reader DataAdapter

Data Reader provides open &

static forward–only connection.

DataAdapter provides a

disconnected data

architechecture.

Single Row can be read at a

Time.

Multiple Rows can be read at a

Time.

Provides record in read-only

mode.

Provides property to

insert,update delete& retrieve

rows using commands.

Good choice for retrieving large

amount of data.

Good choice for retrieving as

well as to insert,update delete

data.

It works quickly It is not works quickly

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2. DATASET

The DataSet is a Disconnected storage &

disconnected in Memory representation of Data.

The DtaSet contains a collection of one or more

DataTable object made up of rows & columns of data,

as well as primary key ,foreign key ,relation

information about the data in the Data Table object.

The data in DataSet can be loaded from any valid data

source like Microsoft SQL server database, an Oracle

database or from a Microsoft Access database.

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DataSet objects are in-memory representations of

data. They contain multiple Datatable objects, which

contain columns and rows, just like normal database

tables.

You can even define relations between tables to

create parent-child relationships.

Create Data Reader Object

Syntax

Dim ds as new DataSet()

or

Dim ds as new DataSet(“Dataset_Name”)

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DATASET

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PROPERTY OF DATASET

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METHODS OF DATASET

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DATA TABLE

DataTable is a collection of DataColumn, DataRow

and Constrain. The concept of DataTable is similar

to the concept of tables in DataBase.

DataTable object allows you to examine data

through collection of rows and columns.

You can store the result of a query in a DataTable

through DataAdapter objects fill method.

Create DataTable object

Syntax: Dim dt as new DataTable ()

Or

Dim dt as new DataTable (“TableName”)

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DATACOLUMN COLLECTION

Each DataTable has a column collection

The concept of DataColumn is similar to the concept

of column in the DataBase table.

DataColumn doesn’t actually contain data but it

contain the information about the structure of the

column.

Create DataColumn

Syntax: Dim col as new DataColumn()

Or

Dim col as new DataColumn(“ColumnName”)

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DATA ROWS COLLECTION

The DataRow and DataColumn objects are

primary components of a DataTable.

Use the DataRow object and its properties and

methods to retrieve and evaluate; and insert,

delete, and update the values in the DataTable.

The DataRowCollection represents the actual

DataRow objects in the DataTable, and the

DataColumnCollection contains the DataColumn

objects that describe the schema of the

DataTable. Use the overloaded Item property to

return or set the value of a DataColumn.

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DATA RELATION OBJECT

DataRelation object allows user to specify

relationship between different columns of different

DataTable objects.

Relationship is useful to provide data integrity and

consistency. Relationship can be established

between two tables by defining a primary key in one

table and using a foreign key in the other table.

Create Data Relation object

Syntax:

Dim dr as new DataRelation(“Relation

Name”, ”ParentColumn”, ”ChildColumn”)

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5.4 Bounded Gridview Step Step 1 : Go to Data Sources and click at "Add New Data

Source".

Step 2 : A new window will be open.

Step 3 : Click the Next button.

Step 4 : Click the Next button.

Step 5 : Click the "New connection" button to make a

new database connection.

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Step 6 : A new window will open asking to

save the connection string.

Step 7 : Click the Next button. In the new

window click the Table node to explore all

the tables of your database.

Step 8 : Click the table node to explore all

columns. Then check the checkbox for each

column to select them. Look at the

following figure.

Step 9 : Click the finish button.

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GTU IMP QUESTION

1) Draw and Explain ADO.net Architecture .

2) Explain DataAdapter object with Example.

3) Explain DataTable, DataRow, and DataColumn

4) Explain DataConnection with Example.

5) Explain CommandObject with Example.

6) Explain (i) Abs (ii) Sqrt (iii)Int() (iv) Rnd()

7) Explain (i) Exp (ii) MAX (iii)Ceil (iv) Pow

8) Explain DataSet in brief.

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