MELJUN CORTES Vb.net handout ado.net

Visual Basic .NET Programming

ADO.NET * Property of STI Page 1 of 15

TOPIC TITLE: ADO.NET Specific Objectives: At the end of the topic session, the students are expected to: Cognitive:

1. Explain the DataSet object 2. Explain how to populate DataSets 3. Explain the relationship in DataSets 4. Explain how to create Constraints. 5. Explain how to update data in a DataSet. 6. Explain data binding.

Affective:

1. Listen to others with respect. 2. Participate in class discussions actively.

MATERIALS/EQUIPMENT:

o topic slides o OHP

TOPIC PREPARATION:

o Have the students research on the following: � DataSet objects � Data Binding

o It is imperative for the instructor to incorporate various kinds of teaching strategies while discussing the suggested topics. The instructor may use the suggested learning activities below to facilitate a thorough and creative discussion of the topic.

o Prepare the slides to be presented in the class.

TOPIC PRESENTATION: The topic will revolve around the overview of classes and objects. This will be the suggested flow of discussion for the course topic:

1. Introduce to the students the topics to be covered in this session.

2. Explain the DataSet object. 3. Explain how to populate DataSets. 4. Explain the relationship in DataSets. 5. Explain how to create Constraints. 6. Explain how to update data in a DataSet. 7. Explain data binding,



The DataSet Object Page 1 of 26

ADO.NET


* Property of STIPage 1 of 26

DataSetDataSetDataSetDataSetObjectObjectObjectObject

� a disconnected, memory resident cache of data

� reads the database and creates an in-

memory copy of that part of that database

that the program needs

� contains DataTables, DataRelation and

Constraints objects

The DataSet Object

The main new feature in ADO.NET is provided by the DataSet object. This object is a disconnected, memory resident cache of data that reads the database and creates an in-memory copy of that part of that database that the program needs. After the data set is created, there is no longer an active connection to the database. Thus, it improves performance because the only time that the program has to connect to with the database server is when reading or writing from the database. It contains DataTables, DataRelation and Constraints objects.

The DataTable object consists of the Columns collection and Rows

collection. These are used to manipulate the fields and query the properties. The DataRelation contains definitions of all the

relationships that exist between the DataTable and DataSet. [The DataSet Object, Page 1 of 26]

Populating DataSets Page 2 of 26

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PopulatingPopulatingPopulatingPopulatingDataSetsDataSetsDataSetsDataSets

� done at runtime

� use DataAdapter to access data

� Example:

Private conServer As

SqlClient.SqlConnection

Public Sub Form1_Load(ByVal

sender As System.Object,

ByVal e As System.EventArgs)

Handles MyBase.Load

conserver = New

SqlClient.SqlConnection()

Dim strConnection As String =

“Integrated Security=True;Data

Source=Localhost;Initial

Catalog=Books;”

conServer.ConnectionString =

strConnection

conserver.Open()

End Sub

Populating DataSets Page 3 of 26

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PopulatingPopulatingPopulatingPopulatingDataSetsDataSetsDataSetsDataSets

� Example: (con’t)

Private Sub Button1_Click ByVal sender

As System.Object, ByVal e As

System.EventArgs) Handles

Button1.Click

Dim adaptSQL As

SqlClient.SqlDataAdapter(“Select

count(*) from Catalogue”,

conserver)

‘the code that will fill the DataSet

Dim datBooks As New DataSet()

adaptSQL.Fill(datBooks, “MyTable”)

‘manipulate data locally using

DataSet

adaptSQL.Update(datBooks, “MyTable”)

End Sub

Populating DataSets

Populating a DataSet is done at runtime. The DataAdapter is used

to access data stored in the database and store the data in DataTable

objects within a DataSet in the application.

The sample codes shown below demonstrate how to populate

DataSets. This example is similar to the code shown in the ‘Populating

a DataTable’ in the previous topic. The DataTable to be populated is

called “MyTable” with data from a database. Private conServer As SqlClient.SqlConnection

Public Sub Form1_Load(ByVal sender As System.Object,

ByVal e As System.EventArgs) Handles MyBase.Load

conserver = New SqlClient.SqlConnection()

Dim strConnection As String = “Integrated

Security=True;Data Source=Localhost;Initial

Catalog=Books;”

conServer.ConnectionString = strConnection

conserver.Open()

End Sub

Private Sub Button1_Click ByVal sender As

System.Object, ByVal e As System.EventArgs) Handles

Button1.Click

Dim adaptSQL As SqlClient.SqlDataAdapter(“Select

count(*) from Catalogue”, conserver)



adaptSQL.Fill(datBooks, “MyTable”)

‘manipulate data locally using DataSet

adaptSQL.Update(datBooks, “MyTable”)

End Sub

[Populating DataSets, Pages 2-3 of 26]



Relationships in DataSet Page 4 of 26

ADO.NET



Relationships Relationships Relationships Relationships inininin DataSetDataSetDataSetDataSet

� DataRelation object

� allows tables to provide relationship with each

other

� contains an array of DataColumn objects that

define the parent column, primary key and child

column or foreign key in the relationship

� Example:


System.Object, ByVal e As

System.EventArgs) Handles Button1.Click

Dim adaptSQL As SqlClient.SqlDataAdapter


adaptSql = New

SqlClient.SqlDataAdapter(“Select ISDN,

title, author, publisher from

Catalogue”, conServer)

adaptSQL.Fill(datBooks, “MyTable1”)

adaptSql = New

SqlClient.SqlDataAdapter(“Select ISDN,

name, address from Publisher”,

conServer)


Relationships in DataSet Page 5 of 26

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Relationships in Relationships in Relationships in Relationships in DataSetDataSetDataSetDataSet

� Example: (con’t)

‘the code that provides the

relationship

Dim relBooksTitile As New

DataRelation(“BooksTitles”,

datBooks.Tables(“MyTable1”).Columns(

“ISDN”),


“ISDN”))

datBooks.Relations.Add(relBooksTitle)

End Sub

Relationships in DataSet

The DataRelation object allows tables to provide relationship with

each other. Each DataRelation object contains an array of

DataColumn objects that define the parent column or columns, primary key and child column or columns or foreign key in the relationship. An example is shown below, which demonstrates how to establish relationship between objects. The relationship is defined by the use of

the DataRelation object. See the line of codes that provides the relationship below.

Private conServer As SqlClient.SqlConnection



conServer = New SqlClient.SqlConnection()



Catalog=Books;”


conServer.Open()

End Sub



Button1.Click

Dim adaptSQL As SqlClient.SqlDataAdapter



adaptSql = New SqlClient.SqlDataAdapter(“Select

ISDN, title, author, publisher from Catalogue”,

conServer)


adaptSql = New SqlClient.SqlDataAdapter(“Select

ISDN, name, address from Publisher”, conServer)


‘the code that provides the relationship

Dim relBooksTitile As New

DataRelation(“BooksTitles”,

datBooks.Tables(“MyTable1”).Columns(“ISDN”),

datBooks.Tables(“MyTable2”).Columns(“ISDN”))

datBooks.Relations.Add(relBooksTitle)

End Sub

[Relationships in DataSet, Pages 4-5 of 26]



Accessing Related Data Pages 4 of 26

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AccessingAccessingAccessingAccessingRelated DataRelated DataRelated DataRelated Data

� GetChildRows method

� used to access related records in a

different table

� Example

Dim BookRow, PubRow As DataRow

Dim TitleRows() As DataRow ‘ Array

of DataRow objects

BookRow =

datBooks.Tables(“MyTable1”).Rows

(0)

TitleRows =

BookRow.GetChildRows(“BooksTitle

s”)

For Each PubRow In TitleRows

ListBox1.Items.Add(PubRow(“title

”).ToString)

Next

Accessing Related Data

The GetChildRows method of a DataRow object is used to access related records in a different table. This method returns an array of

DataRow objects. An example on how to access related records is shown below. The ListBox control is populated with data from an array

of DataRow objects. Dim BookRow, PubRow As DataRow

Dim TitleRows() As DataRow ‘ Array of DataRow objects

BookRow = datBooks.Tables(“MyTable1”).Rows(0)

TitleRows = BookRow.GetChildRows(“BooksTitles”)

For Each PubRow In TitleRows

ListBox1.Items.Add(PubRow(“title”).ToString)

Next

[Accessing Related Data, Page 6 of 26]

Creating Constraints Page 7 of 26

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Creating Creating Creating Creating ConstraintsConstraintsConstraintsConstraints

� Constraint

� a rule used to maintain the integrity of the

data in the DataTable

� Types of constraint classes to DataColumns:

� ForeignKeyConstraint

� UniqueConstraint

� ForeignKeyConstraint

� controls what happens to a child row when a

parent row is updated or deleted

Does not affect related rows.None

Sets related values to their

defaults.

SetDefault

Sets related values to DB Null.SetNull

Deletes or updates any child

records based on the parent record.

Cascade


ADO.NET




� ForeignKeyConstraint Example:

Dim colParent As DataColumn

Dim colChild As DataColumn

Dim fkcBooksTitles As

ForeignKeyConstraint

colParent =


“ISDN”)

colChild =


“ISDN”)

fkcBooksTitles = New

ForeignKeyConstraint(“BooksTitlesFKC

onstraint”, colParent, colChild)

fkcBooksTitles.DeleteRule =

Rule.SetNull

fkcBooksTitles.UpdateRule =

Rule.Cascade

datBooks.Tables(“titles”).Constraints.A

dd(fkcBooksTtiles)

datBooks.EnforceConstraints = True

Creating Constraints A constraint is a rule used to maintain the integrity of the data in the

DataTable. For example, when you delete a value that is used in one

or more related tables, a ForeignKeyConstraint determines whether the values in the related tables are also deleted, set to null values, set to

default values, or whether no action occurs. A UniqueConstraint, on the other hand, simply ensures that all values within a particular table are unique.

There are two types of constraint classes to DataColumns that can be

used to create new constraints namely ForeignKeyConstraint and

UniqueConstraint.

The ForeignKeyConstraint object controls what happens to a child row when a parent row is updated or deleted. The following table shows

the values for the DeleteRule and UpdateRule properties of the

ForeignKeyConstraint. Cascade Deletes or updates any child records

based on the parent record. SetNull Sets related values to DB Null. SetDefault Sets related values to their defaults. None Does not affect related rows.

The example shown below shows how to create and define constraints.

An instance of the ForeignKeyConstraint object is created named

fkcBooksTitles. Then, rules are applied to the fkcBooksTitles.

Next, the constraint is added to the table using the Add method of the

Constraints object.

Dim colParent As DataColumn

Dim colChild As DataColumn

Dim fkcBooksTitles As ForeignKeyConstraint

colParent =

datBooks.Tables(“MyTable1”).Columns(“ISDN”)

colChild =

datBooks.Tables(“MyTable2”).Columns(“ISDN”)




ADO.NET




� UniqueConstraint

� can be added to one column or to an array

of columns

� checks if the values in the columns are

unique

� UniqueConstraint Example

Dim ucTitles As New

UniqueConstraint(“UniqueTitles”,

datBooks.Tables(“titles”).Column

s(“title”))


fkcBooksTitles = New

ForeignKeyConstraint(“BooksTitlesFKConstraint”,

colParent, colChild)

fkcBooksTitles.DeleteRule = Rule.SetNull

fkcBooksTitles.UpdateRule = Rule.Cascade

datBooks.Tables(“titles”).Constraints.Add(fkcBooksTti

les)


On the other hand, the UniqueConstraint can be added to one column or to an array of columns. It checks if the values in the columns are unique. An example is shown below: Dim ucTitles As New UniqueConstraint(“UniqueTitles”,

datBooks.Tables(“titles”).Columns(“title”))


[Creating Constraints, Pages 7-9 of 26]

Using Existing Constraints Page 10 of 26

ADO.NET



Using Existing Using Existing Using Existing Using Existing ConstraintsConstraintsConstraintsConstraints

� FillSchema method

� used to copy constraint information into a

DataSet

� Example:

adaptSQL = New

SqlClient.SqlDataAdapter(“Select

ISDN, title, author, publisher

from Catalogue”, conServer)

adaptSQL.FillSchema(datBooks,

schematype.Source, “Titles”)

adaptSQL.Fill(datBooks, “Titles”)

‘edit some data


Using Existing Constraints

The FillSchema method is used to copy constraint information into a DataSet.

adaptSQL = New SqlClient.SqlDataAdapter(“Select ISDN, title, author, publisher from Catalogue”,

conServer)

adaptSQL.FillSchema(datBooks, schematype.Source,

“Titles”)


‘edit some data


[Using Existing Constraints, Page 10 of 26]

Updating Data in the DataSet Page 11 of 26

ADO.NET



Updating Data Updating Data Updating Data Updating Data in the in the in the in the DataSetDataSetDataSetDataSet

� Adding Rows

� instantiate DataRow object by issuing the

NewRow method of the DataTable

� populate the columns with data

� call the Add method of the DataRows

collection passing the DataRow object

� Example:

Dim newDataRow As DataRow =

datBooks.Tables(“Titles”).NewRow

newDataRow(“title”) = “New York”

newDataRow(“type”) = “business”

datBooks.Tables(“Titles”.Rows.Add(n

ewDataRow)

Updating Data in the DataSet There are three operations that you can do in a DataSet namely add, update and delete data. Adding Rows The following steps are used to add new rows to a table:

1. Instantiate DataRow object by issuing the NewRow method of

the DataTable.

2. Populate the columns with data.

3. Call the Add method of the DataRows collection passing the

DataRow object. The example below demonstrates the steps discussed above in adding rows to a table. Dim newDataRow As DataRow =




ADO.NET




� Editing existing rows

� Call the BeginEdit method of the row.

� Change the data in the columns.

� Call the EndEdit or CancelEdit to

accept or reject the changes.

� Example:

Dim editDataRow As DataRow =

datBooks.Tables(“Titles”).Rows(0

)

editDataRow.BeginEdit()

editdataRow(“Title”) =

editDataRow(“Title”).ToString &

“ 1”

editDataRow.EndEdit()


ADO.NET




� Deleting Data

� Remove method

� Delete method

� Remove method Example

Dim delRow As DataRow =

datBooks.Tables(“Titles”).Rows(0

)

datBooks.Tables(“Titles”).Rows.Rem

ove(delRow)

� Delete method Example


datBooks.Tables(“Titles”).Rows(0)

datBooks.Tables(“Titles”).Rows.Delete(delRo

w)


ADO.NET




� To commit deletion invoke AcceptChangesof the DataSet:

� datBooks.AcceptChanges()

� To undo deletion invoke RejectChanges of the DataSet:

� datBooks.RejectChanges()

datBooks.Tables(“Titles”).NewRow

newDataRow(“title”) = “New York”

newDataRow(“type”) = “business”

datBooks.Tables(“Titles”.Rows.Add(newDataRow)

Editing Rows The following steps are used to edit existing rows in a table:

1. Call the BeginEdit method of the row. 2. Change the data in the columns.

3. Call the EndEdit or CancelEdit to accept or reject the

changes. The example below demonstrates the steps discussed above in editing existing rows in a table. Dim editDataRow As DataRow =


editDataRow.BeginEdit()

editdataRow(“Title”) = editDataRow(“Title”).ToString

& “ 1”

editDataRow.EndEdit()

Deleting Data There are two ways to delete a row:

• Remove method

• Delete method

Example of Remove method is shown below. The Remove method of

the DataRow collection deletes permanently the row from the DataSet (datBooks as instance). Dim delRow As DataRow =


datBooks.Tables(“Titles”).Rows.Remove(delRow)

Example of Delete method is shown below. The Delete method only

marks the row for deletion in the DataSet (datBooks as instance). To

delete it permanently, the AcceptChanges method is called or to undo

the deletion, the RejectChanges method is invoked.



datBooks.Tables(“Titles”).Rows.Delete(delRow)

To commit deletion invoke AcceptChanges of the DataSet: � datBooks.AcceptChanges()

To undo deletion invoke RejectChanges of the DataSet:

� datBooks.RejectChanges()

[Updating Data in the DataSet, Pages 11-14 of 26]



Designing DataSets Page 15 of 26

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Designing Designing Designing Designing DataSetsDataSetsDataSetsDataSets

� Connection Wizard

� Tools > Connect to Database

� click the Change button to select the data

source

Designing DataSets There are a number of designers available in VB.Net to simplify the process of DataSet creation. These include the Connection Wizard and DataAdapter Configuration Wizard. Connection Wizard The Connection Wizard is called when you select the Connect to Database from the Tools menu. The Connection wizard start page is shown below:

To create a connection using the Connection Wizard, perform the following:

1. On the Tools menu, select Connect to Database. The Add Connection dialog box appears.

2. Click the Change button to select the data source. A new window will appear as shown below.

3. Select the data source to be used. For this demonstration, select Microsoft ODBC Data Source then click OK.




ADO.NET




� select a data source then click OK

� on the Data source specification section, click

the Use user or system data source namethen select the MS Access Database

� click OK. Select the Access database file and

then click OK

� open the Server Explorer panel to see the

connection that appears under the Data

Connections


ADO.NET




� DataAdapter Configuration Wizard

� can be used with an existing database

connection

� Adding DataAdapter to Toolbox

� right-click Data from the Toolbox then

click Choose Items

� tick on a data adapter

• (i.e. OleDbDataAdapter)

� click OK

4. Back to the Add Connection page, on the Data source

specification section, click the Use user or system data source name then select the MS Access Database. You use this if you want to select the database using the file dialog control.

NOTE: The view of the Add Connection dialog box varies depending on the selected Data Source in the Change Data Source dialog box. 5. Click OK. A file dialog box appears. Select the Access

database file and then click OK. 6. You are now connected to the database. Open the Server

Explorer panel to see the connection that appears under the Data Connections.

DataAdapter Configuration Wizard The DataAdapter Configuration wizard can be used with an existing database connection. The wizard can be initiated by adding a SqlDataAdapter or OleDbDataAdapter from the Toolbox to a form at design time. It requires the following information:

• Connection name

• Query type

• Details of the query In previous versions of Microsoft Visual Studio (2002 and 2003), the Toolbox was equipped with various data adapters. However, It was removed in the 2005 version. If you want to visually create a data adapter, you must manually add it to the Toolbox. To add data adapter to Toolbox:

1. Right-click the Data section of the Toolbox and click Choose Items. The Choose Toolbox Items dialog box appears.



2. In the .NET Framework Component tab, scroll down and put a

check mark on a data adapter, example the OleDbDataAdapter. 3. Click OK. The selected adapter is added to the Toolbox.

[Designing DataSets, Pages 15-17 of 26]

Data Binding in Windows Forms Page 18 of 26

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Data Binding in Data Binding in Data Binding in Data Binding in Windows FormsWindows FormsWindows FormsWindows Forms

� Data binding

� used to customize the appearance of the

forms

� Types of binding

� Simple Binding

• used to link a control to a single field in a

DataSet

� Complex Binding

• used to link multiple fields in a DataSet


ADO.NET




� Simple Binding Example:Private conServer As SqlClient.SqlConnection

Public Sub Form1_Load(ByVal sender As


System.EventArgs) Handles MyBase.Load



Security=True;Data

Source=Localhost;Initial Catalog=Books;”


conserver.Open()

End Sub




Dim adaptSQL As

SqlClient.SqlDataAdapter(“Select title,

author from Catalogue”, conserver)



adaptSQL.Fill(datBooks, “Catalogue”)

TextBox1.DataBindings.Add(“Text”,

datBooks.Tables(“Catalogue”), “title”)


datBooks.Tables(“Catalogue”), “author”)

End Sub

Data Binding in Windows Forms Data binding is used if you want to customize the appearance of the forms. There are two types of binding namely simple binding and complex binding. These two can be implemented at design time either by using the Properties window or at runtime by using code. Simple Binding Simple binding is used to link a control to a single field in a DataSet. An example is simple binding in a TextBox control, using the DataBindings property; specify which DataSet and which field of a table to bind to which property. The following example shows how to bind data to a TextBox control. Private conServer As SqlClient.SqlConnection






Catalog=Books;”


conserver.Open()

End Sub



Button1.Click


title, author from Catalogue”, conserver)







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� Complex Binding Example:

Private conServer As SqlClient.SqlConnection

Public Sub Form1_Load(ByVal sender As


System.EventArgs) Handles MyBase.Load



Security=True;Data

Source=Localhost;Initial Catalog=Books;”


conserver.Open()

End Sub




Dim adaptSQL As

SqlClient.SqlDataAdapter(“Select title,

author from Catalogue”, conserver)




DataGrid1.DataSource =

datBooks.Tables(“Catalogue”)

End Sub


datBooks.Tables(“Catalogue”), “title”)


datBooks.Tables(“Catalogue”), “author”)

End Sub

Complex Binding Complex binding is used to link multiple fields in a DataSet. For example, complex binding is used for DataGrid control. This control has a DataSource property that allows you to specify the table to be used. The following example shows how to bind data to a DataGrid control. Private conServer As SqlClient.SqlConnection






Catalog=Books;”


conserver.Open()

End Sub



Button1.Click


title, author from Catalogue”, conserver)




DataGrid1.DataSource = datBooks.Tables(“Catalogue”)

End Sub

[Data Binding in Windows Forms, Pages 18-20 of 26]

Demonstration: How to Create a Data Source Demonstrate the following to your students. Before you start the demonstration, create a MS Access database file named StudentDB. Create a table named Student that has the following fields:

• fname

• lname

• age

• course

• address

Save the database file and open the VS 2005 for the demo.

1. To begin, go to File, New Project and name the project as MyDataSource.

2. Click the OK button. VS .Net displays the first form named



Demonstration: How to Create a Data Source Page 21 of 26

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Demonstration: How to Demonstration: How to Demonstration: How to Demonstration: How to Create a Data SourceCreate a Data SourceCreate a Data SourceCreate a Data Source

� File > New Project and name it as

MyDataSource then click OK

� select the ToolBox tab

� select the OleDbDataAdapter from the ToolBox and drop it onto the form

� click New Connection


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� click the Change button

� select Microsoft Access Database File then click OK

Form1.vb. 3. Click once anywhere on the form and then select the ToolBox

tab on the left of the design window. 4. Next, select the OleDbDataAdapter from the ToolBox and drop

it onto the form. Once you release it, it does not actually sit on top of the form but instead, it positions itself onto the component tray. At this point, the Data Adapter Configuration Wizard appears.

NOTE: If you already have an existing connection to the database that you want to use then select the database from the dropdown list and skip steps 5 – 8.

5. Click New Connection. The Add Connection dialog box

appears. 6. In the Add Connection page, click the Change button to change

the data source. A new window will appear as shown below.

7. Select the Microsoft Access Database File then click OK. You are back to the Add Connection dialog box.




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� click the Browse button to locate

StudentDB access database then click OK

� click Next

� select Use SQL Statements then click Next


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� click the Query Builder button

� select the Student table then click Addand Close button

8. Click the Browse button on the Database file name section and locate StudentDB access database. Click OK.

9. Now click Next to advance to the next screen of the wizard where you can use SQL statements, or existing stored procedures, or create new stored procedures.

10. Select Use SQL Statements radio button and click the Next

button. See image on the next page.




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� tick the (All Columns) checkbox

� click the OK button to save and close the window

SELECT student.*

FROM student

� click Next then the Finish button

� right-click the OleDbDataAdapter1 and

select Generate DataSet then click the OK button

� right-click on the OleDbDataAdapter1again then choose Preview Data


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� click the Preview button to view data in then click the Close button

� OleDbDataAdapter, OleDbConnection, and

dataset are now created. This new

dataset can be used in any .Net control of your choice

11. Click the Query Builder button to create your query.

12. Select the Student table from the Add Table dialog box and

click the Add button and then the Close button. The Student table must appear in the Query Builder window.



13. Tick the (All Columns) checkbox in the Student table. Notice

that a query statement appears in the mid-section of the Query Builder window.

14. Click the OK button to save and close the window. You are once again back at the wizard and now you will see the query statement generated in the Query Builder.

SELECT student.*

FROM student

15. Now, click the Next button to display the wizard result and then

click the Finish button to close the wizard. Notice that in the design view of Form1, specifically in the component tray, OleDbConnection1 appears.

16. Right-click the OleDbDataAdapter1 on the component tray and select Generate DataSet. Leave the default settings as is and click the OK button. DataSet1 appears in the component tray.

17. Right-click on the OleDbDataAdapter1 again but this time, choose Preview Data. The Preview Data dialog box appears.

18. Click the Preview button. The data in Student table now

appears in the Preview Data dialog box. Click the Close button. 19. You have just created your first OleDbDataAdapter,

OleDbConnection, and dataset. You could now use this new dataset in any .Net control of your choice.

[Demonstration: How to Create a Data Source, Page 26 of 26]

EVALUATION/GENERALIZATION:

o DataSet class was developed to help you create and manage any type of list-based application.

o The DataTable object consists of the Columns collection and Rows collection which are used to manipulate the fields and query the properties.

o A data adapter is an object that takes data from a database, reads that data, and "fills" a DataSet object with that data.

o The DataRelation object provides relationship in each tables. o The DataRow object has GetChildRows method that is used to

access related records in a different table. o A constraint is a rule used to maintain the integrity of the data in

the DataTable. o There are three operations that you can do in a DataSet namely



add, update and delete data.

o Simple binding is used to link a control to a single field in a DataSet while complex binding is used to link multiple fields in a DataSet.

REFERENCES:

� Microsoft Official Course, (2002), 2373B: Programming with

Microsoft Visual Basic .NET, Microsoft Corporation � Holzner, Steven, (2003), Sams teach yourself Microsoft Visual

Basic.Net 2003 in 21 days, USA, Sams Publishing � Liberty, Jesse, (2003), Learning Visual Basic .NET, USA,

O'Reilly & Associates, Inc

Technology

MELJUN CORTES Vb.net handout ado.net