Ado Net

Agenda  

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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   

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ADO.NET solves these problems  

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Requires COM and Windows® Recordsets don’t travel well across the Internet Connected behavior is hard to work with 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 

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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)

ADO.NET Architecture Presentation Tier Windows Forms MyApp.Exe

DataSet

Internet Intranet

Web Forms IE

DataSet

Business to Business

(BizTalk, for example)

XML

Business Tier

Data Tier

Data Object (Class) DataSet

Data Adapter Data Adapter

ADO.NET ODBC

ODBC Driver

ODBC RDBMS

OLE DB Provider

Application

Connection

OLE DB

.NET Data Provider

OLE DB RDBMS

Command

Data Reader

Data Adapter

SQL Server

ADO.NET Objects 

Connection 

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Command 

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Executes SELECT, INSERT, UPDATE and DELETE commands

Data Reader 

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Connects to data source

Forward-only, read-only stream of data

Data Adapter 

Connects a DataSet to a data source

Working With Data 

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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   

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DataAdapter uses these Command objects for selecting, updating, and so on 

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SelectCommand/DeleteCommand InsertCommand/UpdateCommand Each property contains a Command object

Call the Update method to change data

Call the Fill method to execute the SelectCommand 

Fills a DataSet

DataSet Object 

Relational views of data 



Contains tables, columns, rows, constraints, views, and relations

Disconnected model    

Has no knowledge of data source Array-like indexing Strong typing Supports data binding

DataSet Tables Table Columns Column Constraints Constraint

Rows Row Relations Relation

Summary  

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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