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Accessing data with ADO.NET
Accessing data with ADO.NET
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Objectives
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Introduction
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ADO.NET and other technologies
•
Connected Objects
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Objects List
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Demonstrations
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Using Disconnected Objects in VS.NET
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Disconnected Objects
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Objects List
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Demonstrations
–
Using Disconnected objects in VS.NET
Objectives
•
Introduction
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ADO.NET and other technologies

Why a new data access technology?
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Visual Basic 3 - Data Access Objects (DAO)
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designed to communicate with local file-based databases
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Visual Basic 4 - Remote Data Objects (RDO)
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a fast, lightweight data access layer designed to talk to larger server-based
databases (SQL Server, Oracle…)
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Visual Basic 5 and Visual Studio 97 - ODBCDirect
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combine the power of RDO with the ease of use that DAO provides
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Visual Basic 6 and Visual Studio 6 - ADO
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a data access model we could use easily in server-side scripts (fewer lines
of code, allow us to pass data structures from server to client and back)
Drawbacks of older technologies
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Problems:
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Developers need to build more powerful applications
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work with XML data
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can pass ADO Recordset objects between different tiers in your
application, but cannot combine the contents of multiple
Recordset objects

DataSet into the Fill method of a connected ADO.NET object—the
DataAdapter.
.NET Data Providers
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SQL Client .NET Data Provider
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communicate with SQL Server databases, version 7+
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OLE DB .NET Data Provider
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communicate with various data stores through OLE DB providers
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Each .NET data provider implements the same base classes
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Base classes: Connection, Command, DataReader, Parameter,
Transaction
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their actual names depend on the provider
Connection Strings
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SQL Server
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Provider=SQLOLEDB;Data Source=MyServer\MyInstance; 
Initial Catalog=MyDatabase;User ID=MyUID;Password=MyPass;
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Provider=SQLOLEDB;Data Source=MyServer;
Initial Catalog=MyDb; Integrated Security=SSPI;
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Provider=SQLOLEDB;Data Source=MyServer;
Initial Catalog=MyDatabase; Trusted_Connection=Yes;

Objects List
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Demonstrations
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Using Disconnected objects in VS.NET
Using ADO.NET Objects
Connected Objects
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Connection Object:
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Use it to connect to and disconnect from your database.
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Command Object
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Represent a query against your database (retrieve, modify…), a call
to a stored procedure, a direct request to return the contents of a
specific table
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DataReader Object (data read-only)
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Is designed to help you retrieve and examine the rows returned by
your query quickly
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Transaction Object
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Parameter Object
Connected Objects
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Data Adapter
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Demonstrations
Dim strConn As String = "Provider=Microsoft.Jet.OleDB.4.0; & _
    “Data Source=db1.mdb"
Dim cn As New OleDbConnection(strConn)
cn.Open()
...
cn.Close()
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Open connection