ASP.NET Session 11 12


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ASP.NET Session 11 12

  1. 1. ADO.NET Session-11-12
  2. 2. Objectives • ADO versus ADO.NET • ADO.NET Architecture • Connection Object • Command Object • DataReader Object • DataAdapter Object • DataSet Object • DataView Object • Use ADO.NET to access data in an application
  3. 3. ADO versus ADO.NET Feature ADO ADO.NET Primary Aim Client/server coupled Disconnected collection of data from data server Form of data in memory Uses RECORDSET object (contains one table) Uses DATASET object (contains one or more DATATABLE objects) Disconnected access Uses CONNECTION object and RECORDSET object with OLEDB Uses DATASETCOMMAND object with OLEDB XML capabilities XML aware XML is the native transfer medium for the objects Code Coupled to the language used, various implementation Managed code library – Uses Common Language Runtime, therefore, language agnostic
  4. 4.  Although classic ADO was geared for a two - tiered environment (client - server), ADO.NET addresses a multi - tiered environment.  ADO.NET offers many advanced features and many different ways to retrieve your data and manipulate it before presenting it to the end user.  ADO.NET addresses a couple of the most common data - access strategies that are used for applications today
  5. 5. ADO.NET Architecture
  6. 6. ADO.NET Namespaces • :Core namespace, defines types that represent data • System.Data.Common:Types shared between managed providers • System.Data.OleDb:Types that allow connection to OLE DB compliant data sources • System.Data.SqlClient:Types that are optimized to connect to Microsoft® SQL Server • System.Data.SqlTypes:Native data types in Microsoft® SQL Server
  7. 7. Needed to build a data access application • For OLE DB: using System.Data using System.Data.OleDB • For SQL Server: using System.Data using System.Data.SQLClient
  8. 8. Connection Object • Two provider-specific classes SqlConnection OleDbConnection. This information is provided via a single string called a connection string. You can also store this connection string in the web.config file of your application.
  9. 9.  The OLEDbConnection object, which can provide connection to a wide range of database types like Microsoft Access and Oracle.  The Connection object contains all of the information required to open a connection to the database  With ASP.NET , you will find that there is an easy way to manage the storage of your connection strings using the web.config file.  This is actually a better way to store your connection strings rather than hard-coding them within the code of the application itself.
  10. 10. • To define your connection string within the web.config file, you are going to make use of the <connectionStrings> section. Within this section, you can place an <add> element to define your connection. • What is Web.Config File? • Web.config file, as it sounds like is a configuration file for the Asp .net web application. An Asp .net application has one web.config file which keeps the configurations required for the corresponding application. Web.config file is written in XML(eXtensible Markup Language) with specific tags having specific meanings.
  11. 11. • <connectionStrings> • <add name="FirstSample" connectionString="Data Source=SANDIP;Initial Catalog=siliguri;Persist Security Info=True; • User ID=sa;Pwd=secret;MultipleActiveResultSets= • False;Packet Size=4096;Application Name=&quot;Microsoft SQL Server Management Studio&quot;" • providerName="System.Data.SqlClient" /> • </connectionStrings> • <appSettings> • <add key="FirstSample" value="server=SANDIP;uid=sa;pwd=secret;database=sili guri"/> • </appSettings>
  12. 12. Command object • The Command object uses the Connection object to execute SQL queries. • These queries can be in the form of inline text, stored procedures, or direct table access. • The Command object provides a number of Execute methods that you can use to perform various types of SQL queries.
  13. 13. Property description CommandText This read/write property allows you to set or retrieve either the T-SQL statement or the name of the stored procedure. CommandTimeout This read/write property gets or sets the number of seconds to wait while attempting to execute a particular command. The command is aborted after it times out and an exception is thrown. The default time allotted for this operation is 30 seconds. CommandType This read/write property indicates the way the CommandText property should be interpreted. The possible values are StoredProcedure, TableDirect, and Text.The value of Text means that your SQL statement is inline or contained within the code itself. Connection This read/write property gets or sets the SqlConnection object that should be used by this Command object.
  14. 14. Various Execute methods that can be called from a Command object. Property Description ExecuteNonQuery This method executes the command specified and returns the number of rows affected. ExecuteReader This method executes the command specified and returns an instance of the SqlDataReader class. The DataReader object is a read-only and forward-only cursor. ExecuteRow This method executes the command and returns an instance of the SqlRecord class. This object contains only a single returned row. ExecuteScalar This method executes the command specified and returns the first column of the first row in the form of a generic object. The remaining rows and columns are ignored.
  15. 15. DataReader Object • The DataReader object is a simple forward-only and read-only cursor. • Provides methods and properties that deliver a forward-only stream of data rows from a data source • When a DataReader is used, parts of the ADO.NET model are cut out, providing faster and more efficient data access • It requires a live connection with the data source and provides a very efficient way of looping and consuming all or part of the result set.
  16. 16.  When using a DataReader object, be sure to close the connection when you are done using the data reader.  If not, then the connection stays alive.  The connection utilized stays alive until it is explicitly closed using the Close() method or until you have enabled your Command object to close the connection.  Data Reader is returned as the result of the Command objects,s ExecuteReader method.
  17. 17. void Page_Load(Object sender, EventArgs e) { SqlConnection myConnection; SqlCommand myCommand; SqlDataReader myDataReader; myConnection = new SqlConnection(ConfigurationSettings.AppSettings["strConn"] ); myConnection.Open(); //prepare sql statements myCommand = new SqlCommand("SELECT TOP 10 * FROM EMPLOYEE", myConnection); myDataReader = myCommand.ExecuteReader(); while (myDataReader.Read()) { Response.Write(myDataReader["fname"]);
  18. 18. //Spacing Response.Write(" "); Response.Write(myDataReader["minit"]); //Spacing Response.Write(" "); Response.Write(myDataReader["lname"]); //New Line Response.Write("<br>"); } //cleanup objects myDataReader.Close(); myConnection.Close(); }
  19. 19. DataAdapter Object • The SqlDataAdapter is a special class whose purpose is to bridge the gap between the disconnected DataTable objects and the physical data source. • Provides a set of methods and properties to retrieve and save data between a DataSet and its source data store • Allows the use of stored procedures Connects to the database to fill the DataSet and also update the database • It is capable of executing a SELECT statement on a data source and transferring the result set into a DataTable object.
  20. 20. It is also capable of executing the standard INSERT, UPDATE, and DELETE statements and extracting the input data from a DataTable object. The SqlDataAdapter class also provides a method called Fill().
  21. 21. Summaries • ADO.NET architecture. • Several classes on ADO.NET. • Web Config.