JDS – VB.NET Skill JDS – VB.NET Skill SessionSession

Fall 2004Fall 2004

Presented by Presented by YUHAO LINYUHAO LIN

TOPICSTOPICS

• Visual Studio .NET

• VB.NET Code Structure

• VB.NET Language Basics

• Data Access in .NET

What is .NET ?What is .NET ?

• Microsoft® .NET (released 2001) is Microsoft’s new generation "software platform."  It's a language-neutral environment for writing programs

• Program in any language, run on one operating system

• Includes comprehensive class libraries that provide rich features

What is VB.NET ?What is VB.NET ?

• Visual Basic .NET

• Next generation of Visual Basic

• A programming language in the .NET framework

• Fully object-oriented

Visual Studio .NETVisual Studio .NET

• Available in Software Lab

• Latest version: 2003

• Integrated Development Environment (IDE) for developing .NET applications

Visual Studio .NETVisual Studio .NET

• Create a new project

• Opening an existing project– Open .sln file– Solution Explorer (design vs code view)– Properties Window– Toolbox: many Controls– Task List

Visual Studio .NETVisual Studio .NET

• Code view– Comments– #Regions: collapse– Intellisense– Run / compile– Debug / step into

• Executable file– Location: bin or obj subdirectory

VB.NET Code StructureVB.NET Code Structure

VB.NET

• Import statements

• Namespace– Class

• Functions / Subs• Properties• Class variables

Java

• Package

• Import statements– Class

• Methods• Accessor methods• Class variables

VB.NET Code StructureVB.NET Code Structure

VB.NETimports System.Data.OleDb

namespace TestNamespacepublic class TestClass

sub NewRecord()…

end sub

function GetRecord() as String

…

return strX

end function

End class

end namespace

Javapackage com.deitel.chp08;

import java.io.*;public class Driver {

void newRecord() {

…

}

String getRecord() {

…

return strX;

}

}

VB.NET LanguageVB.NET Language

• Case insensitive– BUT, always be consistent !!!!!

• No semicolon to end statement• One line per statement, & _ for multi-line

statements:str1 = str2 &_ str1 = str2 & str3

str3

• Very wordy, resembles English language• Good for beginners

Programming ReviewProgramming Review

Car myCar = new Car(“Ford”, “Escort”)

What did I do ??

Common Data TypesCommon Data Types

• Integer

• Double

• Boolean

• String

• Array

Dim j as integer = 0

Dim d as double = -3.55

Dim b as boolean = false

Dim s as string = “Yo ^ !”;

Dim Days( ) As Integer = New Integer(6) {1, 2, 3, 4, 5, 6, 7}‘create an array with 7 elements, starting at index 0

end at 6

Data ConversionData Conversion

• Convert.ToType(var);

Ex: Convert.ToInt32(“45”)

Convert.ToDateTime(“12/31/2000”)

Ex:Dim j as integer

Dim s as string = “16”

If IsNumeric(s) Then ‘ check if s is a valid number

J = Convert.ToInt32(s) ‘ convert s to 32-bit integer, assign to J

End If

OperatorsOperators

DESCRIPTION VB.NET Ex JAVA Ex

String concatenation & str1 = str2 & str3 + str1 = str2 + str3

&= str1 &= str2 += str1 += str2

Addition += int1 += int2 += int1 += int2

Add 1 n/a int1 = int1 + 1 ++ int1++

Comparison >=, <= >=, <=

Equality = If j = 1 == if (j == 1)

Inequality Not If Not j = 1 ! if (j != 1)

<> If j <> 1

MethodsMethods

VB.NETFunction:

Function GetMe(ByVal s as String) as String

‘ note the parameter

s = s.Replace(“h”, “hi”)

Return s

End Function

Subroutine:

Sub SetMe(ByVal s as String)

Dim str1 as String = s

‘ nothing to return

End Sub

JavaReturn Method:

String getMe(String s)

{

s = s.replace(“h”, “hi”);

return s;

}

Void Method:

Void setMe(String s)

{

String str1 = s;

}

PropertiesProperties

VB.NET(1 property)

Dim sCustomerName as String = “”

Property CustomerName() As String

Get

Return sCustomerName

End Get

Set(ByVal Value As String)

sCustomerName = Value

End Set

End Property

Java(2 accessor methods)

String sCustomerName = “”;

String getCustomerName()

{

return sCustomerName;

}

void setCustomerName(String name)

{

sCustomerName = name;

}

LoopsLoops

Dim x as Integer = 0

Do While x < 5

x = x + 1

Loop

Dim x as Integer = 0

While x < 5

x = x + 1

End While

For j as Integer = 0 to 10 Step 1

MsgBox(j)

Next

Dim MyArray() as Integer =

{1, 2, 3, 4, 6, 549}

For Each i as Integer in MyArray

MsgBox(i)

Next

Exception HandlingException Handling

• Syntax:Try

…

Catch var as Exception

…

Finally

…

End Try

• Example:‘ try converting a string to int32, then output

whether the conversion is successful

Dim MyInt as integer

Dim bool as Boolean = true

Try

MyInt = Convert.ToInt32(“Not Possible”)

Catch ex as Exception

MsgBox(“Error: “ & ex.Message)

bool = false

Finally

MsgBox(“Conversion successful: “ & bool)

End Try

Database AccessDatabase Access

• ADO.NET (ActiveX Data Objects)– The .NET way to work with data

• Disconnected Architecture

• 2 Data Providers:– SQL Server: specific provider for SQL Server

• Import System.Data.SqlClient

– OLEDB: everything else, basically…• Import System.Data.OleDb

ADO.NETADO.NET

Data Access ComponentsData Access Components

• Connection string – http://www.able-consulting.com/ADO_Conn.htm

• Connection object

• SQL statement

• Command Object & DataReader– OR –

• Data Adapter & DataSet

Connection StringConnection String

SQL Server Data Provider:

"Network Library=DBMSSOCN;Data Source=111.11.111.111,3333;” & _

“Initial Catalog=epics;User Id=epics;Password=jds"

OLEDB Data Provider (SQL Server):

"Provider=sqloledb;" & _

"Data Source=111.11.111.111,3333;" & _

"Initial Catalog=epics;" & _

"User Id=epics;" & _

"Password=jds"

OLEDB Data Provider (Access):

"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=T:\www\mdb\WebInt.mdb"

DataSet vs DataReaderDataSet vs DataReader

• DataReader– Object to access data in a connected,

forward-only, read-only fashion

• DataSet– Data structure to store schema and data in a

disconnected fashion– Useful for editing data offline and later update

to data source

Database ConnectivityDatabase ConnectivityUsing SQL Server Data Provider and DataSet:

Dim strConn as String = "Network Library=DBMSSOCN;Data Source=111.11.111.111,3333;” & _

“Initial Catalog=epics;User Id=epics;Password=jds”

Dim oConn as new SqlConnection(strConn)

Dim strSQL as String = “select * from NODE_PROFILE”

Dim oAdapter as new SqlDataAdapter(strSql, oConn)

Dim ds as new DataSet

oAdapter.Fill(ds, “NODE_PROFILE”)

‘ now we have a DataSet with data from the NODE_PROFILE table

Using OLEDB Data Provider and DataReader:

Dim strConn as String = "Provider=sqloledb;" & "Data Source=111.11.111.111,3333;" & _

"Initial Catalog=epics;" & "User Id=epics;" & "Password=jds“

Dim oConn as new OleDbConnection(strConn)

Dim strSQL as string = “select * from NODE_PROFILE”

Dim oCommand as New OleDbCommand(strSql, oConn)

Dim oReader As OleDbDataReader

oReader = oCommand.ExecuteReader()

‘ now we have a DataReader with data from the NODE_PROFILE table

ADO.NET in JDS.2GO ??ADO.NET in JDS.2GO ??

• Not taking advantage of .NET data providers and data structures

• Using outdated technology: objects from ADODB class

• This semester: possibly transform all of JDS.2GO to ADO.NET-standard

ADO.NETADO.NET

• Hands-on Exercise!!!!!!!!!!!

• Task: build a simple VB.NET application with database connectivity to display the front-end. Based on existing C# code