Chapter 34. The System.Data Namespace
The
System.Data
namespace represents the core of
ADO.NET. It contains the fundamental data container classes such as
DataSet
. Every DataSet
contains a collection of DataTable
instances. Each
DataTable
holds a collection of
DataRow
objects, each of which contains the data
for a single row. These data classes are independent of any ADO.NET
provider. They simply store disconnected data. In addition, the
DataSet
also contains objects that describe
structural information about your data. This structural information,
which is also known as metadata, includes
column-specific settings such as data type (found in
DataColumn
), foreign key and unique column
constraints (represented by ForeignKeyConstraint
and UniqueConstraint
), and relations that link
columns in different tables (represented by
DataRelation
).
Taken together, these objects act like an in-memory relational
database, complete with versioning, column and table information, XML
output, and automatic enforcement of identity and relational
integrity rules. However, these classes are only part of the
System.Data
namespace. You’ll
also find the interfaces that must be implemented by every ADO.NET
provider. These interfaces define connections
(IDbConnection
), commands
(IDbCommand
), data readers
(IDataReader
), parameters
(IDbDataParameter
), transactions
(IDbTransaction
), and data adapters
(IDbDataAdapter
and
IDataAdapter
). These interfaces aren’t just a low-level part of ADO.NET. You’ll need to ...
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