ADO.NET

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ADO.NET

• Rong Li

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• Objectives
• Over view of ADO.NET
• Components in ADO

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What is ADO.NET?

• ADO.NET which is a data-access component of the
  Microsoft .NET Framework works with any component
  on any platform that understands XML.
• ADO.NET employs a disconnected database model. In
  this model, data is retrieved from a database and
  cached on a local machine. The data is
  manipulated on a local machine and connect to a
  database only when records are altered or new
  data is acquired.

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High-level architecture of ADO.NET
Data-Related Components
Managed-provider Components
DataReader
Command
Connection
SQL Server and other OLE DB data store
DataStores
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• In the architecture, two distinct groups of
  classes
• content components
• managed-provider components

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content components

• DataSet
• DataTable
• DataView
• DataRelation

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DataSet

• The DataSet can be viewed as an in-memory view
  of a database. It can contain multiple DataTable
  and DataRelation objects. ADO.NET involves
  disconnected datasets, the DataSet object
  provides a number of methods so that all data
  manipulation done to the DataSet can be
  reconciled with a actual database at a later time.

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DataSet (continue)

• DataSet does not tie to an underlying
  representation such as SQL Server or Microsoft
  Access, it is portable. Its data format is
  self-described in its schema, and its data is in
  pure XML.

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DataTable

• DataTable represents a table of data and thus
  contains a collection of DataColumns and a
  collection of DataRow.

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DataView

• Different customized views of a DataTable can be
  created, each with different sorting and
  filtering criteria. Individual records can be
  traversed, searched and edited.
• In ADO.NET, DataView serves data binding to
  Windows Forms and Web Forms.

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DataRelation

• With DataRelation, the relationships between
  DataTable objects can be defined. Client
  components can inspect an individual table or
  navigate the hierarchy of tables through these
  relationships.

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Managed Providers

• Managed provider is a term used for a group of
  .NET components that implement a fixed set of
  functionality set forth by the ADO.NET
  architecture. This enforces a common interface
  for accessing data.
• Microsoft provides two managed providers in its
  current release of ADO.NET OLE DB and SQL. Both
  of them implement a set of interfaces that access
  the appropriate data store.

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managed-provider components

• Connection object
• Command object
• Data Reader object
• DataAdapter object

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Connection object

• Both OleDbConnection and SqlConnection implement
  System.Data.IDbConnection. Transaction support
  for the ADO.NET connection object has been moved
  to a Transaction object.

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Command object

• The command objects are the only way we can make
  execution requests to insert, update, and delete
  data in ADO.NET. All commands are associated with
  a connection object through the SqlCommands or
  the OleDbCommands Connection property. In
  ADO.NET, the result of executing a query command
  is a data reader object or any class implementing
  the IDataReader for custom reading needs.

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Data Reader object

• Use a data reader object to access records in a
  forward-only, sequential order. It is efficient.
  Because this is a server-side cursor, the
  connection to the server is open throughout the
  reading of data.

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DataAdapter object

• DataAdapter object acts as the bridge between the
  data source and the disconnected DataSet.
• Each DataAdapter maps only one DataTable in the
  DataSet, but multiple adapters can be filled to

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• Steps of a typical usage of data adapter
• Create a data-adapter object
• Set up a query string for the internal
  SelectCommand object
• Set up a connection string for the
  SelectCommands Connection object
• Set up InsetCommand, UpdateCommand, DeleteCommand
  query string and connection
• Call Fill() to fill a given dataset with the
  results from a query string
• Make changes and call the adapters Update()
  method with a changed DataSet