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DataAdapter
In
ADO.NET, the data adapter object acts as a two-way bridge between a data source
and the DataSet object.
The
DataSet is a disconnected container of data, and the adapter takes care of
filling it and submitting its data back to a particular data source.
From
an abstract point of view, a data adapter is similar to a command and
represents another way of executing a command against the data source.
The
big difference between commands and data adapters is just in the way each one
returns the retrieved data. A query command returns a read-only, forward-only
cursor—the data reader. The data adapter performs its data access, grabs all
the data, and packs it into an in-memory
container—the DataSet or DataTable.
DataSet
The
dataset is a disconnected, in-memory representation of data. It can be
considered as a local copy of the relevant portions of the database. The
DataSet is persisted in memory and the data in it can be manipulated and
updated independent of the database. When the use of this DataSet is finished,
changes can be made back to the central database for updating. The data in
DataSet can be loaded from any valid data source like Microsoft SQL server
database, an Oracle database or from a Microsoft Access database.
Inside
a DataSet, much like in a database, there are tables, columns, relationships,
constraints, views, and so forth.
The
ADO.NET DataSet is the core component of the disconnected architecture of
ADO.NET. The DataSet is explicitly designed for data access independent of any
data source. As a result it can be used with multiple and differing data
sources, used with XML data, or used to manage data local to the application.
The DataSet contains a collection of one or more DataTable objects made up of rows
and columns of data, as well as primary key, foreign key, constraint, and
relation information about the data in the DataTable objects.
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