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ADO.NET is data access layer
ActiveX Data Objects
Microsoft developed ActiveX Data Objects (ADO) as a COM( Component Object Model ) wrapper around OLE DB for Databases.
using System;
using System.Data;
using System.Data.OleDb;
// Step 1.Open Database Connection
OleDbConnection conn = new
OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\inventory\\inventory\\db\\invent.mdb;");
// Step 2.Connection database opened
conn.Open();
// Step 3.Create DataSet and Command objects
OleDbCommand cmd = new OleDbCommand(
"SELECT * FROM empr4r",
conn);
// Step 4.Execute the command
cmd.ExecuteScalar();
// Step 5.Closed this connection
conn.Close();
The System.Data is main namespace of ADO.Net and it has DataSet and classes (DataTable, DataColumn, DataRow, DataRelation, Constraint,etc ). System.Data has a namespace System.Data.Common.
ADO.NET has three different ways of accessing database information directly which are: 1.Commands :-have classes SqlCommand and OleDbCommand , used directly to retrieve results from database queries.Command classes always support the IDbCommand interface.Commands classesare used to get a scalar result (the first column of the first row of a result set) or out parameters of a stored procedure.sort of data is retrieved using IDbCommand.ExecuteScalar() and IDbCommand.ExecuteNonQuery() 2.DataReaders has SqlDataReader and OleDbDataReader.These classes are provide something similar to ADO's Recordset using a forward-only cursor. 3.DataSets classes Microsoft uses DataReaders within the managed providers' DataAdapters to fill DataSet
ADO.NET to access data by using the new .NET Framework data providers which are given below: 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).
The ADO.NET classes are found in System.Data.dll and are integrated with the XML classes in System.Xml.dll. ADO.NET is a set of classes that expose data access services to the .NET developer. There are two central components of ADO.NET classes: the DataSet, and the .NET Framework Data Provider.
Data Provider is a set of components including: 1.The Connection object (SqlConnection, OleDbConnection, OdbcConnection, OracleConnection) 2.The Command object (SqlCommand, OleDbCommand, OdbcCommand, OracleCommand) 3.The DataReader object (SqlDataReader, OleDbDataReader, OdbcDataReader, OracleDataReader) 4.The DataAdapter object (SqlDataAdapter, OleDbDataAdapter, OdbcDataAdapter, OracleDataAdapter). DataSet object represents a disconnected cache of data which is made up of DataTables and DataRelations that represent the result of the command.
Dataset is: 1.Disconnected Recordset objects similar to an array. 2.Supports disconnected data access and operations. 3.Scalability, Provide greater scalability because users no longer have to be connected to the database all the time. DataSet object is made up of two objects: 1.DataTableCollection object containing null or multiple DataTable objects 2.DataRelationCollection object containing null or multiple DataRelation objects which establish a parent/child relation between two DataTable objects.
There are two type of dataset in Ado.net: 1.Typed DataSet: Typed DataSet is derived from the base DataSet class and then uses information in an XML Schema file (.xsd file) in order to generate a new class. Create a typed DataSet without designer - manually a.Call the command prompt (cmd) at the location of the XSD schema file. b.Use the XSD.EXE utility to create the class for the typed DataSet. 2.Untyped DataSet : Untyped DataSet is not defined by a schema, instead, you have to add tables, columns and other elements to it yourself, either by setting properties at design time or by adding them at run time.
There are following way to populate Dataset: a.By using DataAdapter objects and Fill method. b.By creating DataTable, DataColumn and DataRow objects programmatically. c.Read an XML document or stream into the DataSet. d.Merge (copy) the contents of another DataSet, with the Merge method.
DataAdapter object is links the database and a Connection object with the ADO.NET-managedDataSet object through its SELECT and action query Commands. Means it works like a bridge DataAdapter specified that which data is to move into and out of the DataSet. DataAdapter provide references to SQL statements or stored procedures that are invoked to read or write to a database. The DataAdapter provides four properties that allow us to control how updates are made to the server: SelectCommand UpdateCommand InsertCommand DeleteCommand
The DataAdapter includes three main methods: 1.Fill (populates a DataSet with data). 2.FillSchema (queries the database for schema information that is necessary to update). 3.Update (to change the database, DataAdapter calls the DeleteCommand, the InsertCommand and the UpdateCommand properties).
To bind some elements of a data source with some graphical elements of an application, this ability known as DataBinding. The data in Windows Forms is bound by calling DataBindings. Windows Forms allows you to bind easily to almost any structure that contains data. Windows Forms Controls support two types of data binding: a.Simple Data Binding: To display a single data element, means to display a column value from a DataSet table, in a control. It is possible to bind any property of a control to a given data value. Simple Data Binding can be performedby two ways: 1.At design time using DataBindings property of a control 2.Dynamically at run time. This is the type of binding typical for controls such as a TextBox control or Label control that displays typically only a single value. b.Complex Data Binding: To bind more than one data element, typically more than one record in a database, or to more than one of any other type of bindable data element. DataGrid, ListBox and ErrorProvider controls support complex data binding.
ADO.net includes many objects you can use to work with data. Some of the primary objects are: 1. The SqlConnection Object 2. The SqlCommand Object 3. The SqlDataReader Object 4. The DataSet Object 5. The SqlDataAdapter Object
SqlConnection object is like a c# object.The object declare like that: SqlConnection conn = new SqlConnection( "Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI"); This argument is called a connection string. It is define as: Data Source: Identifies the server. Integrated Security: Set to SSPI to make connection with user's Windows login User ID: Name of user configured in SQL Server. Password: Password matching SQL Server User ID. Using a SqlConnetion the connection creates as: 1.Instantiate the SqlConnection. 2.Open the connection. 3.Pass the connection to other ADO.NET objects. 4.Perform database operations with the other ADO.NET objects. 5.Close the connection.
SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);
Above syntax is written to instantiating a SqlCommand object. It takes a string parameter that holds the command you want to execute and a reference to a SqlConnection object.
Instantiate a new command with a query and connection
SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);
Call Execute reader to get query results
SqlDataReader rdr = cmd.ExecuteReader();
Passing the command string and connection object to the constructor. Then we obtain a SqlDataReader object by calling the ExecuteReader method of the SqlCommand object, cmd.
To insert data into a database, use the ExecuteNonQuery method of the SqlCommand object. Instantiate a new command with a query and connection SqlCommand cmd = new SqlCommand(insertString, conn); Call ExecuteNonQuery to send command cmd.ExecuteNonQuery();
The ExecuteNonQuery method is also used for updating data. The following code shows how to update data: 1.Prepare command string 2.Instantiate a new command with command text only SqlCommand cmd = new SqlCommand(updateString) 3.Set the Connection property cmd.Connection = conn; 4.Call ExecuteNonQuery to send command cmd.ExecuteNonQuery();
To deleting data also using the ExecuteNonQuery method. The following example shows how to delete a record from a database with the ExecuteNonQuery method: 1.Prepare command string 2.Instantiate a new command SqlCommand cmd = new SqlCommand(); 3.Set the CommandText property cmd.CommandText = deleteString; 4.Set the Connection property cmd.Connection = conn; 5.Call ExecuteNonQuery to send command cmd.ExecuteNonQuery();
There is a little different way to creating object of a SqlDataReader like other object creation in C#. Necessary call ExecuteReader on a command object. SqlDataReader rdr = cmd.ExecuteReader(); The ExecuteReader method of the SqlCommand object, cmd , returns a SqlDataReader instance.
SqlDataReader rdr = cmd.ExecuteReader();
The typical method of reading from the data stream returned by the SqlDataReader is to iterate through each row with a while loop.
while (rdr.Read())
{
string conta = (string)rdr["ContactName"];
string comp = (string)rdr["CompanyName"];
string cty = (string)rdr["City"];
Console.Write("{0,-25}", conta);
Console.Write("{0,-20}", cty);
Console.Write("{0,-25}", comp);
Console.WriteLine();
}
Dataset object create as: DataSet dsStudents = new DataSet(); DataSet constructor doesn't require parameters. However there is one overload that accepts a string for the name of the DataSet, which is used if you were to serialize the data to XML. Since that isn't a requirement for this example, I left it out. Right now, the DataSet is empty and you need a SqlDataAdapter to load it.
SqlDataAdapter holds the SQL commands and connection object for reading and writing data. It initializes with a SQL select statement and connection object:
SqlDataAdapter daStudent = new SqlDataAdapter(
"select StudentID, CollegeName from Students", conn);
The SQL select statement specifies what data will be read into a DataSet.
The connection object, conn, should have already been instantiated, but not opened.
SqlCommandBuilder is instantiated with a single constructor parameter of the SqlDataAdapter, daStudent, instance.
SqlCommandBuilder cmdBldr = new SqlCommandBuilder(daStudent);
SqlCommandBuilder will read the SQL select statement (specified when the SqlDataAdapter was instantiated), infer the insert, update, and delete commands.
Once you have a DataSet and SqlDataAdapter instances, you need to fill the DataSet. Here's how to do it, by using the Fill method of the SqlDataAdapter:
SqlDataAdapter daStudent = new SqlDataAdapter
("select StudentID, CollegeName from Students", conn);
SqlCommandBuilder cmdBldr = new SqlCommandBuilder(daStudent);
daStudent.Fill(dsStudent, "Students");
Fill method, takes two parameters: a DataSet and a table name.
Some basic namespaces are: 1.System.Data (basics types) 2.System.Data.OleDb (OLEDB Provider) 3.System.Data.SqlClient (Microsoft Sql Server provider) 4.System.Data.Common 5.System.Data.SqlTypes 6.System.Data.Odbc (ODBC Provider) 7.System.Data.Odbc.OracleClient (Oracle Provider) 8.System.Data.SqlServerCe (Compact framework)
Connection-Oriented Scenario: 1.Always accessing current data 2.Low number of concurrent data accesses 3.Many write accesses situation 4.IDbConnection, IDbCommand, IDataReader Disconnected Scenario: 1.Modification in Dataset is not equal to modification in data source 2.Many concurrent read accesses situation 3.Dataset, Data table, DbDataAdapter
1.To cache data and pass to a different tier Dataset forms the best choice and it has decent XML support 2.Dataset is a disconnected architecture; DataReader has live connection while reading data. 3.To access data from more than one table Dataset forms the best choice. 4.If we need to move back while reading records, data reader does not support this functionality. 5.A biggest drawback of Dataset is speed. As Dataset carry considerable overhead because of relations, multiple table etc speed is slower than DataReader. Always try to use DataReader wherever possible, as it is meant especially for speed performance.
objCommand.CommandText = "Tab1"
objDataAdapter.Fill(objDataSet, "Tab1")
objCommand.CommandText = "Tab2"
objDataAdapter.Fill(objDataSet, "Tab2")
Above code shows how to load multiple Data Table objects in one Dataset object. Sample code shows two tables Tab1 and Tab2 in object ObjDataSet.
lstdata.DataSource = objDataSet.Tables("Tab1").DefaultView
In order to refer Tab1 Data Table, use Tables collection of Datasets and the Default view object will give you the necessary output.
1.Using dataset retrieve data from two databases like Oracle and SQL server and merge them in one dataset, with recordset this is not possible. 2.Recordset uses COM. But all representation of Dataset is using XML. 3.Dataset can be transmitted on HTTP while Recordset cannot be transmitted.
1.We have recordset in ADO and in ADO.NET we have dataset. 2.In recordset we can only have one table. If we want to accommodate more than one table we need to do inner join and fill the recordset. Dataset can have multiple tables. 3.All data persist in XML as compared to classic ADO where data persisted in Binary format also.
Connection Pooling make a single connection instance, which allows that instance to connect to all the databases. It does not open and close the connection object multiple times.
1.ReadXML: Read’s a XML document in to Dataset. 2.GetXML: This is a function, which returns the string containing XML document. 3.Writexml: This writes a XML data to disk.
ADO stands for ActiveX Data Object .ADO.NET is an object-oriented set of libraries that allows to interact with data sources. The data source is a database, but it could also be a text file, an Excel spreadsheet, or an XML file.ADO .NET consists of classes that allow a .NET application to connect to the data source, executes commands and manage disconnected data. One of the key Differences between ADO.NET and other database technologies is how it deals with Challenge with different data sources, that means, the code you use to connect to an SQL Database will not differ that much to the one connecting to an Oracle Database.
The ASP.NET AJAX Control Toolkit includes several extender controls that can be used to enhance the client functionality of Web server controls. Before you add an extender control to a server control in the following procedure, you must install the ASP.NET AJAX Toolkit. You can download the Control Toolkit from the “ASP.NET AJAX Control Toolkit” Web site. 1.Switch to Design view. 2.If the page does not already contain a ScriptManager control, from the AJAX Extensions tab of the Toolbox, drag one onto the page. 3.From the Standard tab of the Toolbox, drag a Button control onto the page. 4.If the Common Button Tasks shortcut menu does not appear, right-click the Button control and then click Show Smart Tag. 5.On the Common Button Tasks menu, click Add Extender. 6.In the Extender Wizard, in the Choose the functionality to add to Button1 list, click ConfirmButtonExtender, and then click OK. 7.In the Properties window, expand the Extenders tab, and then expand Button1_ConfirmButtonExtender. 8.Set the ConfirmText property to Continue?
AJAX(Asynchronous JavaScript And XML) is not a new programming language, but a new way to use existing standards. AJAX is the art of exchanging data with a server, and update parts of a web page without reloading the whole page. The main purpose of Ajax is to provide a simple and standard means for a web page to communicate with the server without a complete page refresh.
Steps: Start Visual Studio, Click on File -> New Website -> Under Visual Studio Installed templates -> Select ASP.NET Ajax-Enabled Site. Enter a location & select OK. If using Visual Studio 2008 Web Developer Express Ajax comes along with it (so no need of a separate installation).Using Visual Studio Web Developer Express 2005 & versions above it, Ajax based applications may easily be created. Note that the Ajax Framework & Ajax Extensions should be installed (In case of VS 2005).
ASP.NET AJAX is a free framework to implement Ajax in asp.net web applications, for quickly creating efficient and interactive Web applications that work across all popular browsers. The Ajax Framework is powered with 1 - Reusable Ajax Controls 2 - Support for all modern browsers 3 - Access remote services and data from the browser without tons of complicated script.
The ScriptManager manages all ASP.NET AJAX resources on a page and renders the links for the ASP.NET AJAX client libraries, which lets you use AJAX functionality like PageMethods, UpdatePanels etc. It creates the PageRequestManager and Application objects, which are prominent in raising events during the client life cycle of an ASP.NET AJAX Web page. It also helps you create proxies to call web services asynchronously. The ScriptManager control (that we may drag on a web form) is actually an instance of the ScriptManager class that we put on a web page. The ScriptManager manages all the ASP.NET Ajax controls on a web page. Using ScriptManager class: 1 - All resources managing on a web page. 2 - Partial page updates 3 - Interact with UpdatePanel Control. 4 - Information Release whether. 5 - Provied Facility to access Web Services Method 6 - Providing access to ASP.NET authentication role.
1.If the network bandwidth is slow,end user confused because no page postback full running. 2.Distributed applications running Ajax will need a central mechanism for communicating with each other
In case of Master page scenario in your application and the MasterPage contains a ScriptManager control, then you can use the ScriptManagerProxy control to add scripts to content pages.A page can contain only one ScriptManager control. Also, if you come across a scenario where only a few pages in your application need to register to a script or a web service, then its best to remove them from the ScriptManager control and add them to individual pages, by using the ScriptManagerProxy control. That is because if you added the scripts using the ScriptManager on the Master Page, then these items will be downloaded on each page that derives from the MasterPage, even if they are not needed, which would lead to a waste of resources.
All controls residing inside the UpdatePanel will be partial postbacked.An UpdatePanel control is a holder for server side controls that need to be partial postbacked in an ajax cycle.The UpdatePanel enables you to add AJAX functionality to existing ASP.NET applications. It can be used to update content in a page by using Partial-page rendering. By using Partial-page rendering, you can refresh only a selected part of the page instead of refreshing the whole page with a postback.
There are 5 AJAX controls. 1. ScriptManager 2. UpdatePanel 3. UpdateProgress 4. Timer 5. ScriptManageProxy
ASP.NET AJAX is a terminology by Microsoft for implementation of AJAX, which is a set of extensions to ASP.NET. These components allow you to build rich AJAX enabled web applications, which consists of both server side and client side libraries.
AJAX is based on internet standards, and uses a combination of: 1. XMLHttpRequest object (to exchange data asynchronously with a server) 2. JavaScript/DOM (to display/interact with the information) 3. CSS (to style the data) 4. XML (often used as the format for transferring data)
The XMLHttpRequest object is used to exchange data with a server. With the XMLHttpRequest object Browser can retrieve and submit XML data directly to a Web server without reloading the page. To convert XML data into renderable HTML content, use the client-side Extensible Stylesheet Language Transformations (XSLT) to compose HTML elements for presentation. Property: 1. Onreadystatechange 2. readyState 3. responseBody 4. responseTextresponseXML 5. StatusstatusText Method 1. abort 2. getAllResponseHeaders: 3. getResponseHeader 4. open 5. send
Features: 1. Improved efficiency. 2. As user requirement significant parts of a Web page's processing are performed in the browser. 3. UI elements- progress indicators, tool tips, and pop-up windows. 4. Partial-page updates that refresh only the parts of the Web page that have changed. 5. Client integration with ASP.NET application services for forms authentication, roles, and user profiles. 6. Auto-generated proxy classes. 7. Provide a framework that lets you customize of server controls to include client capabilities.
The two main Microsoft AJAX Library classes that raise events during the client life cycle of a page: 1. Application and 2. PageRequestManager classes. When partial-page rendering with UpdatePanel controls is enabled, the key client events are the events of the PageRequestManager class. These events enable you to handle many common scenarios. These include the ability to cancel postbacks, to give precedence to one postback over another, and to animate UpdatePanel controls when their content is refreshed. 1. Sys.WebForms.PageRequestManager Events: initializeRequest: Raised during initialization of an asynchronous postback. beginRequest: Raised before processing of an asynchronous postback starts, pageLoading: Raised after a response to an asynchronous postback is received from the server, but before any content on the page is updated. pageLoaded: Raised after all content on the page is refreshed as the result of either a synchronous or an asynchronous postback. endRequest: Use this event to provide customized error notification to users or to log errors. 2. Sys.Application Events: init: Raised only once when the page is first rendered after all scripts have been loaded, but before objects are created. load: Raised after all scripts have been loaded and objects in the application have been created and initialized. unload: Raised before all objects in the client application are disposed.
Use the following code to determine whether AJAX functionality is enabled for a page in C# Code:
ScriptManager sm = ScriptManager.GetCurrent(Page)
if (sm == null)
{
// ASP.NET AJAX functionality is not enabled for the page.
}
else
{
// AJAX functionality is enabled for the page.
}
To determine whether partial page rendering is supported for a page, you can modify this code to use the EnablePartialRendering and the SupportsPartialRendering property of the ScriptManager control.
If the functionality of an extender control is no longer needed, you can remove the extender control. 1.Switch to Design view. 2.Select the Button control, and then on the Common Button Tasks menu, click Remove Extender. 3.In the Extenders attached to Button1 list, select ConfirmButtonExtender. 4.Click Remove, and then click OK.
If you want to adds client functionality to a Button control when users confirm to submit a form to the server then extender controls can use. ASP.NET AJAX extender controls enhance the client capabilities of standard ASP.NET Web server controls such as TextBox controls, Button controls, and Panel controls by using one or more extender controls to provide a richer user experience in the browser, and you also add ASP.NET AJAX extender controls to Visual Studio and work with them as you do with other controls. You can create your own extender controls and source for extender controls is the ASP.NET AJAX Control Toolkit.
Visual Studio supports the following extender control features: 1.Adding extender controls. 2.Removing extender controls. 3.Setting extender control properties. 4.Managing extender controls
Extender Controls in the AJAX Control Toolktit: 1.CascadingDropDown 2.CollapsiblePanelExtender 3.ConfirmButtonExtender 4.FilteredTextBoxExtender 5.ModalPopupExtender 6.PasswordStrength 7.RoundedCornersExtender 8.TextBoxWatermarkExtender
Two classes:
1.ExtenderControl:
The ExtenderControl class enabled to programmatically add AJAX functionality to an ASP.NET server control and inherits from the Control class and implements the IExtenderControl interface. The Control class defines the properties, methods, and events that are shared by all ASP.NET server controls.
Inheritance Hierarchy:
System.Object
System.Web.UI..::.Control
System.Web.UI.ExtenderControl
2.IExtenderControl: The ExtenderControl base class performs an explicit test to make sure that a ScriptManager control exists on the page. However, if you want to create extender controls and the page does not contain an ScriptManager control, you can create a class that implements the IExtenderControl interface directly.
Inheritance Hierarchy:
System.Object
System.Web.UI.Control
System.Web.UI.IExtenderControl
ASP.NET provides the Sys.Debug class for debugging client applications. By calling methods of the Sys.Debug class, you can display objects in readable form at the end of the page, show trace messages, use assertions, and break into the debugger. The following table lists the methods of the Sys.Debug class. Sys.Debug.assert(condition, message, displayCaller): Checks for a condition, and if the condition is false, displays a message and prompts the user to break into the debugger. Sys.Debug.clearTrace(): Clears all trace messages from the TraceConsoletextarea element. Sys.Debug.traceDump(object, name): Dumps an object to the debugger console and to the TraceConsoletextarea element, if available. Sys.Debug.fail(message): Displays a message in the debugger's output window and breaks into the debugger. Sys.Debug.trace(text): Appends a text line to the debugger console and to the TraceConsoletextarea element, if available.
ASP.NET Web server controls that enable you to add AJAX functionality to an ASP.NET Web page. AJAX functionality includes refreshing parts of a page with a partial-page update and therefore avoiding a full-page postback. 1. ScriptManager Control Overview: Manages client script for AJAX-enabled ASP.NET pages 2. Timer Control Overview: Performs postbacks at defined intervals. 3. UpdatePanel Control Overview: Enables you to refresh selected parts of the page instead of refreshing the whole page with a postback. 4. UpdateProgress Control Overview: Enables you to provide status information about partial-page updates in UpdatePanel controls.
The ASP.NET AJAX Timer control performs postbacks at defined intervals. If Timer control used with an UpdatePanel control, you can enable partial-page updates at a defined interval. You can also use the Timer control to post the whole page. You use the Timer control when you want to do the following: 1. Periodically update the contents of one or more UpdatePanel controls without refreshing the whole Web page. 2. Run code on the server every time that a Timer control causes a postback. 3. Synchronously post the whole Web page to the Web server at defined intervals