darshan institute of engineering & technology for diploma ... · darshan institute of...

Darshan Institute of Engineering & Technology for Diploma Studies Unit-5

1 Dept: CE AWT (3360706) Piyush Bhut

ADO.NET ARCHITECTURE

ADO.Net is a large set of .Net classes that enable us to retrieve and manipulate data, and update data

sources, in very many different ways.

The ADO.NET architecture has two main parts:

Data Provider (Connected Objects or Connection oriented objects)

Data Set (Disconnected objects or Connectionless objects)

Data Provider The .NET framework Data Provider are components that have been explicitly designed for data

manipulation and fast, forward-only, read-only access to data.

.NET Framework data provider is used for connecting to a database, executing commands, and

retrieving results.

The following lists the data providers that are included in the .NET framework.

Data Provider Description

SQL Server Provides data access for Microsoft SQL server.

Uses the System.Data.SqlClient namespace.

OLEDB For data sources exposed by using OLEDB.

Uses the System.Data.OleDb namespace.

ODBC For data sources exposed by using ODBC.

Uses the System.Data.Odbc namespace.

Oracle For Oracle data sources.

Uses the System.Data.OracleClient namespace.

The Data Provider has four core objects:



Connection

The Connection object is the first component of ADO.NET. The connection object opens a connection

to your data source.

Connection object helps in accessing and manipulating a database. Database transactions are also

dependent upon the Connection object.

Important properties of the SqlConnection object

ConnectionString - A connection string provides the information that a provider needs to

communicate with a particular database. The Connection String includes parameters such as Server

name and Database name, as well as security information such as user name and password.

Important methods of the SqlConnection object

Open – opens the connection

Close – close the connection

Imports System.Data.SqlClient Dim objConn As New SqlConnection objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial Catalog=Demo;Integrated Security=True" objConn.Open() Label1.Text = "Connection open" objConn.Close() Label2.Text = "Connection closed"

Command

The Command object is used to perform action on the data source. Command object can execute

stored procedures and SQL commands.

You can execute SQL queries to return data in a DataSet or a DataReader object. Command object

performs the standard Select, Insert, Delete and Update SQL operations.

Command object supports a CommandType that specifies how a command string is interpreted.

Text – An SQL command defining the statements to be executed at the data source.

StoredProcedure – The name of the stored procedure. You can use the parameters property of a

command to access input and output parameters.

TableDirect – The name of a table.

Command objects methods for executing commands based on return value.

ExecuteReader – Returns a DataReader object.

ExecuteScalar – Returns a single scalar value.

ExecuteNonQuery – Executes a command that does not return any rows.

ExecuteXMLReader – Returns an XMLReader.

Dim objcmd As New SqlCommand

objcmd.Connection = objConn

objcmd.CommandType = CommandType.Text

objcmd.CommandText = "insert into Student(StudentID, StudentName) values (1,'abc')"

objcmd.ExecuteNonQuery()



Data Reader

The DataReader is built as a way to retrieve and examine the rows returned in response to your query

as quickly as possible.

The data returned by a DataReader is always read only. This class was built to be a lightweight forward

only, read only, way to run through data quickly.

DataReader object works in connected model.

Important methods of the SqlDataReader object

Read – Moves to the next row.

NextResult – Moves to the next result.

objcmd.CommandText = "select * from Student"

Dim objDR As SqlDataReader

objDR = objcmd.ExecuteReader()

While objDR.Read

Label3.Text += objDR("StudentName") + " ".ToString

End While

Data Adapter

The Data Adapter provides the bridge between the Data Set object and the data source.

The Data Adapter uses command object to execute SQL commands at the data source to both load the

Data Set with data and reconcile changes that were made to the data in the dataset back to the data

source.

Using an adapter you can read, add, update and delete records in a data source. An adapter has

following most useful properties.

PROPERTY DESCRIPTION

DeleteCommand Represents a DELETE statement or stored procedure for deleting records from the data source.

objcmd.DeleteCommand.CommandText = "DELETE FROM Student WHERE StudentID = 1 ";

InsertCommand

Represents an INSERT statement or stored procedure for inserting a new record to The data source.

objcmd.InsertCommand.CommandText = "INSERT INTO Student(StudentID,StudentName) VALUE (2, 'smith')";

SelectCommand Represents a SELECT statement or stored procedure can be used to select records from a data source.

objcmd.SelectCommand.CommandText = "SELECT * FROM Student";

UpdateCommand Represents an UPDATE statement or stored procedure for Updating recording in a data source.

objcmd.UpdateCommand.CommandText = "UPDATE Student SET StudentName = 'smith1' WHERE StudentID = 2";

TableMappings Represents a collection of mappings between actual data source table and a DataTable object.



Important methods of the SqlDataAdapter object

FillSchema - This method adds a DataTable to a DataSet.

Fill – This method fills data records from a DataAdapter to a DataSet object.

Update - This method stores data from a data set to the data source.

Data Set

The dataset object is central to supporting disconnected, distributed data scenarios with ADO.NET.

The dataset is a memory-resident representation of data that provides consistent relational

programming model regardless of the data source.

The dataset represents a complete set of data, including related tables, constraints, and relationship

among the table.

The dataset has two major objects:

The DataTableCollection

The DataRelationCollection

The DataTableCollection

The DataTableCollection contains all the DataTable objects in a DataSet.

A DataTable is defined in the System.Data namespace and represents a single table of memory

resident data.

A DataTable contains a collection of rows represented by DataRowCollection which contains the data

in the table.

It contains a collection of columns represented by a DataColumnCollection, and constraints

represented by a ConstraintCollection, which together define the schema of the table.

The DataRelationCollection

A relationship represented by the DataRelation object, associates rows in one DataTable with rows in

another DataTable.

A relationship is analogous to a join path that might exist between primary and foreign key columns in

a relational database.

A DataRelation identifies matching columns in two tables of a DataSet.

The essential element of a DataRelation are:

The name of the relationship

The name of the tables being related

The related column in each table

Relationships can be built with more than one column per table by specifying an array of DataColumn

objects as the key columns.

When you add a relationship to the DataRelationCollection, you can optionally add a UniqueKey

Constraint and a ForeignKeyConstraint to enforce integrity constraints when changes are made to

related column values.

Important properties of DataSet object:



Tables - The Tables propertly allows us to retrieve the tables contained in the DataSet. This

property returns a DataTableCollection object.

Important properties and methods of DataTable object:

Columns - Returns the Columns collection.

Rows - Returns the Rows collection.

NewRow - Creates a new DataRow.

SqlCommandBuilder class in ADO.NET

Provides the feature of reflecting the changes made to a DataSet.

The SqlCommandBuilder object automatically generates the values contained within the

SqlDataAdapter's InsertCommand, UpdateCommand and DeleteCommand properties based on the

initial SelectCommand.

Dim objConn As New SqlConnection

objConn.ConnectionString="Data Source=PRB-PC\SQLEXPRESSREPORT;Initial Catalog=Demo;Integrated

Security=True"

objConn.Open()




objcmd.CommandText = "select * from Student"

Dim objDA As New SqlDataAdapter()

Dim objDS As New DataSet("StudentDS")

objDA.SelectCommand = objcmd

objDA.FillSchema(objDS, SchemaType.Source, "Student")

objDA.Fill(objDS, "Student")

objConn.Close()

Dim objDTStudent As DataTable

objDTStudent = objDS.Tables("Student")

Dim objCB As New SqlCommandBuilder(objDA)

Dim row As DataRow

row = objDTStudent.NewRow

row("StudentID") = 6

row("StudentName") = "piyush"

objDTStudent.Rows.Add(row)

objConn.Open()

objDA.Update(objDS, "Student")

For i = 0 To objDS.Tables("Student").Rows.Count - 1

Label3.Text += objDS.Tables("Student").Rows(i).Item("StudentName") + " ".ToString

Next



DataView

The DataView provides different views of the data stored in a DataTable.

That is we can customize the views of data from a DataTable. DataView can be used to sort, filter, and

search the data in a DataTable , additionally we can add new rows and modify the content in a

DataTable.

We can create DataView in two ways. Either we can use the DataView constructor, or we can create a

reference to the DefaultView property of the DataTable.

Important properties of DataView object

RowFilter - Property that gets or sets the expression used to filter the rows.

Sort - Property that gets or sets the columns and sort orders to apply.


objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT;Initial Catalog=Demo;Integrated

Security=True"

Dim str As String = "select * from Student"

Dim objDA As New SqlDataAdapter(str, objConn)

Dim objDS As New DataSet()

objDA.Fill(objDS, "Student")

objConn.Close()

Dim objDV As New DataView(objDS.Tables(0))

objDV.RowFilter = "StudentName='abc'"

objDV.Sort = "StudentID Desc"

GridView1.DataSource = objDV

GridView1.DataBind()

GridView

GridView control provides more flexibility in displaying and working with data from your database in

comparison with any other controls. The GridView control enables you to connect to a datasource and

display data is tabular format, however you have bunch of options to customize the look and feel.

When it is rendered on the page, generally it is implemented through <table> HTML tag.

RowCommand - Fires when a button is clicked on any row of GridView.(Event)

DataBind - Binds the data source to the GridView control.

Insert, Update, Delete and DataBinding operation CountryList.aspx <asp:HyperLink ID="hlAddCountry" runat="server" NavigateUrl="~/AddEditCountry.aspx">Add Country</asp:HyperLink> <asp:Button ID="btnDisplay" runat="server" Text="Display" /> <asp:GridView ID="dgvCountry" runat="server"> <Columns > <asp:TemplateField HeaderText ="Delete"> <ItemTemplate>

https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview(v=vs.110).aspx



<asp:Button ID ="btnDelete" runat ="server" Text="Delete" CommandName ="DeleteRecord" CommandArgument ='<%# Eval("CountryID") %>' />

</ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText ="Edit"> <ItemTemplate>

<asp:HyperLink id="hlEdit" runat ="server" Text="Edit" NavigateUrl ='<%#"~/AddEditCountry.aspx?CountryID=" + Eval("CountryID").ToString() %>'> </asp:HyperLink>

</ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> CountryList.aspx.vb Protected Sub dgvCountry_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles dgvCountry.RowCommand If e.CommandName = "DeleteRecord" Then Dim objConn As New SqlConnection objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial

Catalog=Demo;Integrated Security=True" objConn.Open() Dim objcmd As New SqlCommand objcmd.Connection = objConn objcmd.CommandType = CommandType.Text objcmd.CommandText = "Delete from Country where CountryID=" +

e.CommandArgument.ToString() objcmd.ExecuteNonQuery() dgvCountry.DataBind() objConn.Close() End If End Sub

Protected Sub btnDisplay_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnDisplay.Click Dim objConn As New SqlConnection objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial Catalog=Demo;Integrated Security=True" objConn.Open() Dim objcmd As New SqlCommand objcmd.Connection = objConn objcmd.CommandType = CommandType.Text objcmd.CommandText = "Select CountryID, CountryName, CountryCode From Country" Dim objDR As SqlDataReader = objcmd.ExecuteReader() dgvCountry.DataSource = objDR dgvCountry.DataBind() End Sub



AddEditCountry.aspx

<table> <tr><h1>Country Entry Form</h1></tr> <tr><asp:Label ID="lblMessage" runat="server" EnableViewState="False"></asp:Label></tr>

<tr><td>*</td> <td>Country Name</td> <td>:</td> <td><asp:TextBox ID="txtCountryName" runat="server"></asp:TextBox></td> <td><asp:RequiredFieldValidator ID="rfvCountryuName" runat="server"

ControlToValidate="txtCountryName" Display="Dynamic" ErrorMessage="Enter Country Name" ForeColor="Red" ValidationGroup="Country"></asp:RequiredFieldValidator></td>

</tr> <tr><td>Country Code</td><td>:</td> <td><asp:TextBox ID="txtCountryCode" runat="server"></asp:TextBox></td></tr> <tr><asp:Button ID="btnSave" runat="server" Text="Save" ValidationGroup="Country"/></tr> </table> AddEditCountry.aspx.vb

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If Not Page.IsPostBack Then

If Request.QueryString("CountryID") = "" Then

lblMessage.Text = "Add Mode"

Else

lblMessage.Text = "Edit Mode, Edit Country Table with CountryID : " +

Request.QueryString("CountryID").ToString()

FillCountryData(Convert.ToInt32(Request.QueryString("CountryID")))

End If

End If

End Sub

Sub FillCountryData(ByVal CountryID As Int32)


objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial Catalog=Demo;Integrated

Security=True"

objConn.Open()




objcmd.CommandText = "Select CountryID, CountryName, CountryCode From Country Where

CountryID=" + CountryID.ToString()

Dim objDR As SqlDataReader = objcmd.ExecuteReader()

If objDR.HasRows = True Then

While objDR.Read



txtCountryName.Text = objDR("CountryName").ToString()

txtCountryCode.Text = objDR("CountryCode").ToString()

End While

End If

objConn.Close()

End Sub

Protected Sub btnSave_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSave.Click



Security=True"

objConn.Open()




If Request.QueryString("CountryID") = "" Then

objcmd.CommandText = "INSERT INTO Country(CountryName, CountryCode) VALUES('" +

txtCountryName.Text.Trim() + "','" + txtCountryCode.Text.Trim() + "')"


lblMessage.Text = "Data Inserted Successfully"

txtCountryName.Text = ""

txtCountryCode.Text = ""

txtCountryName.Focus()

objConn.Close()

Else

objcmd.CommandText = "Update Country SET CountryName='" + txtCountryName.Text.Trim() + "',

CountryCode='" + txtCountryCode.Text.Trim() + "' WHERE CountryID=" +

Request.QueryString("CountryID").ToString().Trim()




objConn.Close()

Response.Redirect("~/Default.aspx")

End If

End Sub

DataList

The DataList Web server control displays data in a format that you can define using templates and

styles. The DataList control is useful for data in any repeating structure, such as a table.

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist(v=vs.85).aspx



Template property and Description:

ItemTemplate: Contains the HTML elements and controls to render once for each row in the data

source.

AlternatingItemTemplate: Contains the HTML elements and controls to render once for every

other row in the data source. Typically, you use this template to create a different look for the

alternating rows, such as a different background color than the color that is specified in

the ItemTemplate property.

SelectedItemTemplate: Contains the elements to render when the user selects an item in

the DataList control. Typically, you use this template to visually distinguish the selected row with a

different background or font color.

EditItemTemplate: Specifies the layout of an item when it is in edit mode. This template typically

contains editing controls, such as TextBox controls.

HeaderTemplate and FooterTemplate: Contains the text and controls to render at the beginning

and end of the list, respectively.

SeparatorTemplate: Contains the elements to render between each item. A typical example might

be a line (using an HR element).

Important properties of DataList Control:

RepeatColumns: The number of columns to display.

RepeatDirection: The direction to render the cells. Possible values are Horizontal and Vertical.

Important Event of DataList Control:

ItemCommand - Occurs when any button is clicked in the DataList control.

Insert, Update, Delete and DataBinding operation AddEditProduct.aspx

<table>

<tr>

<td><asp:Label ID="lblProductName" runat="server" Text="Product Name"></asp:Label></td>

<td><asp:TextBox ID="txtProductName" runat="server"></asp:TextBox></td></tr>

<tr>

<td><asp:Label ID="lblProductImage" runat="server" Text="Image"></asp:Label></td>

<td><asp:FileUpload ID="fuProductImage" runat="server" /></td></tr>

<tr>

<td><asp:Label ID="lblProductPrice" runat="server" Text="Price"></asp:Label></td>

<td><asp:TextBox ID="txtPrice" runat="server"></asp:TextBox></td></tr>

<tr>

<td><asp:Label ID="lblProductDiscount" runat="server" Text="Discount"></asp:Label></td>

<td><asp:TextBox ID="txtDiscount" runat="server"></asp:TextBox></td></tr>

<tr>

<td><asp:Label ID="lblProductColor" runat="server" Text="Color"></asp:Label></td>

<td><asp:TextBox ID="txtColor" runat="server"></asp:TextBox></td></tr>

<tr>

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.itemtemplate(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.alternatingitemtemplate(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.selecteditemtemplate(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.edititemtemplate(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.headertemplate(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.footertemplate(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist.separatortemplate(v=vs.85).aspx

https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.datalist(v=vs.110).aspx



<td><asp:Button ID="btnSave" runat="server" Text="Save" /></td>

<td><asp:Label ID="lblMessage" runat="server" Text="Label"></asp:Label></td></tr>

</table>

AddEditProduct.aspx.vb



If Request.QueryString("ProductID") = "" Then

lblMessage.Text = "Add Mode"

Else

lblMessage.Text = "Edit Mode" + Request.QueryString("ProductID").ToString()

FillProductData(Convert.ToInt32(Request.QueryString("ProductID")))

End If

End If

End Sub

Sub FillProductData(ByVal ProductID As Int32)



Security=True"

objConn.Open()




objcmd.CommandText = "SELECT [ProductName], [Price], [Discount], [Color] FROM [Product] Where

ProductID=" + ProductID.ToString


If objDR.HasRows = True Then

While objDR.Read

txtProductName.Text = objDR("ProductName").ToString()

txtPrice.Text = objDR("Price").ToString()

txtDiscount.Text = objDR("Discount").ToString()

txtColor.Text = objDR("Color").ToString()

End While

End If

objConn.Close()

End Sub

Protected Sub btnSave_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSave.Click





Security=True"

objConn.Open()




If fuProductImage.HasFile Then

fuProductImage.SaveAs("D:\VS\Diploma 6th 2015\ADOTest\images\" & _fuProductImage.FileName)

End If

If Request.QueryString("ProductID") = "" Then

objcmd.CommandText = "INSERT INTO Product(ProductName, Price,ProductImage,Discount,Color)

VALUES('" + txtProductName.Text.Trim() + "','" + txtPrice.Text.Trim() + "','~/images/" +

fuProductImage.PostedFile.FileName + "','" + txtDiscount.Text.Trim + "','" + txtColor.Text.Trim + "')"


txtProductName.Text = ""

txtPrice.Text = ""

txtColor.Text = ""

txtDiscount.Text = ""

txtProductName.Focus()

objConn.Close()

Else

objcmd.CommandText = "Update Product SET ProductName='" + txtProductName.Text.Trim() + "',

Price='" + txtPrice.Text.Trim() + "',ProductImage='~/images/" + fuProductImage.PostedFile.FileName +

"',Discount='" + txtDiscount.Text.ToString + "',Color='" + txtColor.Text.ToString + "' WHERE ProductID="

+ Request.QueryString("ProductID").ToString().Trim()


txtProductName.Text = ""

txtPrice.Text = ""

txtColor.Text = ""

txtDiscount.Text = ""

objConn.Close()

Response.Redirect("~/ProductList.aspx")

End If

End Sub

ProductList.aspx

<asp:DataList ID="dlProduct" runat="server" CellPadding="2" CellSpacing="2" RepeatColumns="3"

RepeatDirection="Horizontal" OnItemCommand="dlProduct_ItemCommand">

<HeaderTemplate>

Product Information

</HeaderTemplate>



<ItemTemplate>

<table border="2" style="width: 150px">

<tr><td style="text-align: center">

<asp:Label ID="ProductNameLabel" runat="server" Text='<%# Eval("ProductName") %>' />

</td></tr>

<tr><td style="text-align: center">

<asp:Image ID="ProductImage" runat="server" ImageUrl='<%# Eval("ProductImage") %>'

Height="200" Width="200" />

</td></tr>

<tr><td>Price:<asp:Label ID="PriceLable" runat="server" Text='<%# Eval("Price") %>' /></td></tr>

<tr><td>Discount:<asp:Label ID="DiscountLabel" runat="server" Text='<%# Eval("Discount") %>' />

</td></tr>

<tr><td>Color:<asp:Label ID="ColorLabel" runat="server" Text='<%# Eval("Color") %>' /></td></tr>

<tr><td><asp:HyperLink ID="hlEdit" runat="server" Text="Edit"

NavigateUrl='<%#"~/AddEditProduct.aspx?ProductID=" + Eval("ProductID").ToString() %>'>

</asp:HyperLink></td></tr>

<tr><td><asp:Button ID="btnDelete" runat="server" Text="Delete"

CommandName="DeleteRecord" CommandArgument='<%# Eval("ProductID") %>' /></td></tr>

</table>

</ItemTemplate>

</asp:DataList>

ProductList.aspx.vb




objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial

Catalog=Demo;Integrated Security=True"

objConn.Open()




objcmd.CommandText = "SELECT ProductName, Price, ProductImage, Discount, Color FROM Product"


dlProduct.DataSource = objDR

dlProduct.DataBind()

End If

End Sub

Protected Sub dlProduct_ItemCommand(ByVal source As Object, ByVal e As

System.Web.UI.WebControls.DataListCommandEventArgs) Handles dlProduct.ItemCommand



If e.CommandName = "DeleteRecord" Then


objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial

Catalog=Demo;Integrated Security=True"

objConn.Open()




objcmd.CommandText = "Delete from Product where ProductID=" + e.CommandArgument.ToString


dlProduct.DataBind()

objConn.Close()

Response.Redirect("~/ProductList.aspx")

End If

End Sub

Repeater

The Repeater control is used to display a repeated list of items that are bound to the control. The

Repeater control may be bound to a database table, an XML file, or another list of items.

Repeater is a Data Bind Control. Data Bind Controls are container controls. Data binding is the process

of creating a link between the data source and the presentation UI to display the data. ASP .Net

provides rich and wide variety of controls, which can be bound to the data.

Comment.aspx

<table >

<tr><td><asp:Label ID="lblName" runat="server" Text="Name"></asp:Label></td>

<td><asp:TextBox ID="txtName" runat="server"></asp:TextBox></td></tr>

<tr><td><asp:Label ID="lblSubject" runat="server" Text="Subject"></asp:Label></td>

<td><asp:TextBox ID="txtSubject" runat="server"></asp:TextBox></td></tr>

<tr><td><asp:Label ID="lblComment" runat="server" Text="Comment"></asp:Label></td>

<td><asp:TextBox ID="txtComment" runat="server"

TextMode="MultiLine"></asp:TextBox></td></tr>

<tr><td> </td>

<td><asp:Button ID="btnSubmit" runat="server" Text="Submit" /></td>

</tr></table>

<asp:Repeater ID="rpComment" runat="server">

<ItemTemplate>

<table border ="2" style="background-color:#EBEFF0; width:500px">

<tr><td>Subject:<asp:Label ID="lblSubject" runat="server" Text='<%#Eval("Subject") %>'

Font-Bold="true"/></td></tr>



<tr><td ><asp:Label ID="lblComment" runat="server"

Text='<%#Eval("Comment")%>'/></td></tr>

<tr><td>Post By:<asp:Label ID="lblUser" runat="server" Font-Bold="true"

Text='<%#Eval("Name") %>'/></td></tr>

<tr><td>Created Date:<asp:Label ID="lblDate" runat="server" Font-Bold="true"

Text='<%#Eval("PostedDate") %>'/></td></tr>

</table>

</ItemTemplate>

<SeparatorTemplate > <br /> </SeparatorTemplate>

</asp:Repeater>

Comment.aspx.vb

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click Dim objConn As New SqlConnection objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial Catalog=Demo;Integrated Security=True" objConn.Open() Dim objcmd As New SqlCommand objcmd.Connection = objConn objcmd.CommandType = CommandType.Text objcmd.CommandText = "INSERT INTO CommentInfo(Name, Subject, Comment, PostedDate) VALUES('" +

txtName.Text.Trim() + "','" + txtSubject.Text.Trim() + "','" + txtComment.Text.Trim + "','" + DateTime.Now + "')"

objcmd.ExecuteNonQuery() objConn.Close() txtName.Text = "" txtSubject.Text = "" txtComment.Text = "" txtName.Focus() BindRepeaterData() End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load BindRepeaterData() End Sub

Sub BindRepeaterData() Dim objConn As New SqlConnection objConn.ConnectionString = "Data Source=PRB-PC\SQLEXPRESSREPORT; Initial Catalog=Demo;Integrated Security=True" objConn.Open() Dim objcmd As New SqlCommand objcmd.Connection = objConn objcmd.CommandType = CommandType.Text objcmd.CommandText = "SELECT Name, Subject, Comment, PostedDate from CommentInfo" Dim objDR As SqlDataReader = objcmd.ExecuteReader()



rpComment.DataSource = objDR rpComment.DataBind() End Sub

AJAX

AJAX (Asynchronous JavaScript and XML) is the technique that can be used to have communication

between the client and server without needing a postback. The benefit of avoiding postback is faster

response to the user, the page in the browser is not changed/refreshed/posted so the user can

continue to use it while data is sent to the server.

AJAX is a technology that facilitates this asynchronous communication between the client and server.

In traditional web pages the entire page is loaded after a postback. The entire page is replaced, the

browser has to dismiss the old one and then draw the new one.

Major benefits of AJAX functionality in a website include:

Partial page updates - Only the portion of the page that needs updating is posted back and not the

whole page.

Faster user response - Since only subsets of data moves between the client and server, the results

are shown quickly.

Enhanced user interface - With AJAX, desktop like user interface with progress indicators and

timers can be implemented.

Enhanced features - with AJAX features like autocomplete can be implemented (For Example,

TextBox to display words that begin with the prefix typed into the textbox).

ScriptManager

To use ASP.NET AJAX, you need to place a new web control on your page. This control is the

ScriptManager, and it’s the brains of ASP.NET AJAX.

It has the basic syntax:

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>



If you create an 'Ajax Enabled site' or add an 'AJAX Web Form' from the 'Add Item' dialog box, the web

form automatically contains the script manager control. The ScriptManager control takes care of the

client-side script for all the server side controls.

UpdatePanel

Ajax updatepanel will help us to avoid full postback of the page i.e., avoid refresh of the whole page

content with postback and allows only partial postbacks. By using Ajax updatepanel we can refresh

only required part of page instead of refreshing whole page.

Ajax updatepanel contains property called UpdateMode this property is used to specify whether

UpdatePanel is always refreshed during a partial render or if it refresh only when a particular trigger

hit. By default updatepanel contains UpdateMode="Always" if we want to set it conditionally we need

to change this property UpdateMode="Conditional".

Ajax updatepanel control contains two child tags those are ContentTemplate and Triggers.

ContentTemplate is used to hold the content of the page means suppose we designed page with some

controls we will place controls inside of the ContentTemplate.

Triggers we used in a situation like need to refresh updatepanel only whenever I click some button

control in that situation I will define those controls with this Triggers child tag.

UpdatePanelDemo.aspx


<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">

<ContentTemplate >

<asp:Label ID="Label1" runat="server" Text="Update Panel 1"></asp:Label>

<asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>

<asp:Button ID="Button2" runat="server" Text="Update Both Panel" />

<asp:Button ID="Button3" runat="server" Text="Update This Panel" />

</ContentTemplate>

</asp:UpdatePanel>


<ContentTemplate>

<asp:Label ID="Label3" runat="server" Text="Update Panel 2"></asp:Label>

<asp:Label ID="Label4" runat="server" Text="Label"></asp:Label>

</ContentTemplate>

<Triggers><asp:AsyncPostBackTrigger ControlID="Button2" EventName="Click" /></Triggers>

</asp:UpdatePanel>

UpdatePanelDemo.aspx.vb

Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click

Label2.Text = DateTime.Now.ToString


End Sub






End Sub

UpdateProgress

UpdateProgress controls to display the progress of partial-page updates. If a page contains

UpdatePanel controls, you can also include UpdateProgress controls to keep users informed about the

status of partial-page updates. You can use one UpdateProgress control to represent the progress of

partial-page updates for the whole page. Alternatively, you can include an UpdateProgress control for

every UpdatePanel control.

Important properties of UpdateProgress

AssociatedUpdatePanelID – ID of the UpdatePanel control from which it is associated with.

DisplayAfter – value in milliseconds before the UpdateProgress control is displayed.

ProgressTemplate – template that defines the content of the UpdateProgress control.

UpdateProgressDemo.aspx



<ContentTemplate>

<table>

<tr><td>Country Name</td>

<td><asp:TextBox ID="txtCountryName" runat="server"></asp:TextBox></td></tr>

<tr><td>Country Code</td>

<td><asp:TextBox ID="txtCountryCode" runat="server"></asp:TextBox></td></tr>

<tr><td><asp:Label ID="lblMessage" runat="server" Text="Label"></asp:Label></td>

<td><asp:Button ID="Button1" runat="server" Text="Add Country" /></td></tr>

</table>

</ContentTemplate>

</asp:UpdatePanel>

<asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel1">

<ProgressTemplate >

<img src ="ajax-loader.gif" />

</ProgressTemplate>

</asp:UpdateProgress>

UpdateProgressDemo.aspx.vb


System.Threading.Thread.Sleep(5000)



https://msdn.microsoft.com/en-us/library/system.web.ui.updateprogress(v=vs.140).aspx





Security=True"

objConn.Open()




objcmd.CommandText = "INSERT INTO Country(CountryName, CountryCode) VALUES('" +

txtCountryName.Text.Trim() + "','" + txtCountryCode.Text.Trim() + "')"


lblMessage.Text = "Data Inserted Successfully"



txtCountryName.Focus()

objConn.Close()

End Sub

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