Introduction to ADO.NET Jenny Chang Student Ambassador to Microsoft CSU – Los Angeles Agenda – Introduce you to ADO.NET – Describe the connected layer of ADO.NET as implemented by .NET data providers – Describe the disconnected layer of ADO.NET as implemented by the DataSet – Demonstrate integration of ADO.NET within Visual Studio Why ADO.NET? • ADO works great, but – Requires COM and Windows® – Recordsets don’t travel well across the Internet – Connected behavior is hard to work with • ADO.NET solves these problems – Uses XML under the covers for all data transport – XML has no runtime/transport requirements • No special code required to marshal across the Internet • ADO.NET requires new mindset – All data access disconnected – All data transport uses XML What Is ADO .NET? • ADO.NET is a collection of classes, interfaces, structures, and enumerated types that manage data access from relational data stores within the .NET Framework – These collections are organized into namespaces: • System.Data, System.Data.OleDb, System.Data.SqlClient, etc. • ADO.NET is an evolution from ADO. – Does not share the same object model, but shares many of the same paradigms and functionality! Connected Or Disconnected? • System.Data namespace contains disconnected set of objects – DataSet, DataTable, DataRow, and so on • Specific namespaces (System.Data.OleDb and System.Data.SqlClient) contain connected objects – SqlDataAdapter/OleDbDataAdapter – SqlConnection/OleDbConnection – SqlDataReader/OleDbDataReader Connected Or Disconnected? With ADO, a fundamental question is: Where is the data managed? On the client? On the server? A mixture of the two? The answer in ADO …it depends on the cursor you are using. With ADO.NET: Data is always on the client (via DataSet) or on its way to the client (via IDataReader) ADO.NET Architecture Presentation Tier Windows Forms MyApp.Exe DataSet Business Tier Data Tier Internet Web Forms Intranet Data Object (Class) IE Data Adapter DataSet XML DataSet Data Adapter Business to Business (BizTalk, for example) ADO.NET .NET Data Provider ODBC Driver ODBC ODBC Connection RDBMS OLE DB Provider Application Command OLE DB OLE DB RDBMS Data Reader SQL Server Data Adapter ADO.NET Objects • Connection – Connects to data source • Command – Executes SELECT, INSERT, UPDATE and DELETE commands • Data Reader – Forward-only, read-only stream of data • Data Adapter – Connects a DataSet to a data source Working With Data • If you need full data access, use DataAdapter object (SQLDataAdapter, OleDbDataAdapter) • DataAdapter represents a set of data commands and a database connection – Fills a DataSet (using Fill method) – Updates data (using Update method) Working With Data • Use Fill method to fill the DataSet – DataSet provides local cache for disconnected data – All data marshaled as XML • Make changes in cached data • Use Update method to write changes from cached data back to data source Getting Data Into A DataSet • DataAdapter has four Command properties – SelectCommand/DeleteCommand – InsertCommand/UpdateCommand – Each property contains a Command object • DataAdapter uses these Command objects for selecting, updating, and so on – Call the Update method to change data • Call the Fill method to execute the SelectCommand – Fills a DataSet DataSet Object Relational views of data DataSet Tables Contains tables, columns, Table rows, constraints, Columns views, and relations Column Constraints Disconnected model Constraint Has no knowledge Rows of data source Row Relations Array-like indexing Relation Strong typing Supports data binding DEMO: Setting Up Connections in Visual Studio.NET Summary • ADO.NET provides a rich API for working with data • ADO.NET has been designed to support legacy architectures as well as Internet- enabled, n-tier designs • The .NET Framework’s extensive XML support means greater reach for all of your data-enabled applications References • Using ADO.NET (VB.NET) http://msdn.microsoft.com/library/en- us/Dndotnet/html/Usingadonet.asp?frame=true • ADO.NET Quick Tutorials (C#, VB.NET, JScript) http://samples.gotdotnet.com/quickstart/howto/default .aspx?url=/quickstart/howto/doc/adoplus/adoplusovervi ew.aspx • Download Tech Talks Slides & Handouts http://jenny.sybay.com/dotnet Questions? Don’t Forget to Fill Out the Evaluation Form & Win Some Prizes!
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