In a disconnected scenario such as the Internet, ADO.NET provides the tools to request, update, and reconcile data in multiple tier systems. The ADO.NET architecture is also implemented in client applications, such as Windows Forms, or HTML pages created by ASP.NET.

The centerpiece of the ADO.NET architecture is the DataSet class. Each DataSet can contain multiple DataTable objects, with each DataTable containing data from a single data source, such as SQL Server.

Each DataTable contains a DataColumnCollection--a collection of DataColumn objects--that determines the schema of each DataTable. The DataType property determines the type of data held by the DataColumn. The ReadOnly and AllowDBNull properties let you further guarantee data integrity. The Expression property lets you construct calculated columns.

If a DataTable participates in a parent/child relationship with another DataTable, the relationship is constructed by adding a DataRelation to the DataRelationCollection of a DataSet object. When such a relation is added, a UniqueConstraint and a ForeignKeyConstraint are both created automatically, depending on the parameter settings for the constructor. The UniqueConstraint guarantees that values that are contained in a column are unique. The ForeignKeyConstraint determines what action will happen to the child row or column when a primary key value is changed or deleted.

Using the System.Data.SqlClient namespace (the.NET Framework Data Provider for SQL Server), the System.Data.Odbc namespace (the.NET Framework Data Provider for ODBC), the System.Data.OleDb namespace (the.NET Framework Data Provider for OLE DB), or the System.Data.OracleClient namespace (the .NET Framework Data Provider for Oracle), you can access a data source to use together with a DataSet. Each .NET Framework data provider has a corresponding DataAdapter that you use as a bridge between a data source and a DataSet.

 Classes

	Class	Description
	Constraint	Represents a constraint that can be enforced on one or more DataColumn objects.
	ConstraintCollection	Represents a collection of constraints for a DataTable.
	ConstraintException	Represents the exception that is thrown when attempting an action that violates a constraint.
	DataColumn	Represents the schema of a column in a DataTable.
	DataColumnChangeEventArgs	Provides data for the ColumnChanging event.
	DataColumnCollection	Represents a collection of DataColumn objects for a DataTable.
	DataException	Represents the exception that is thrown when errors are generated using ADO.NET components.
	DataRelation	Represents a parent/child relationship between two DataTable objects.
	DataRelationCollection	Represents the collection of DataRelation objects for this DataSet.
	DataRow	Represents a row of data in a DataTable.
	DataRowBuilder	Infrastructure. The DataRowBuilder type supports the .NET Framework infrastructure and is not intended to be used directly from your code.
	DataRowChangeEventArgs	Provides data for the RowChanged, RowChanging, OnRowDeleting, and OnRowDeleted events.
	DataRowCollection	Represents a collection of rows for a DataTable.
	DataRowComparer	Returns a singleton instance of the DataRowComparer<(Of <(TRow>)>) class.
	DataRowComparer<(Of <(TRow>)>)	Compares two DataRow objects for equivalence by using value-based comparison.
	DataRowExtensions	Defines the extension methods to the DataRow class. This is a static class.
	DataRowView	Represents a customized view of a DataRow.
	DataSet	Represents an in-memory cache of data.
	DataSetSchemaImporterExtension	This member supports the .NET Framework infrastructure and is not intended to be used directly from your code.
	DataSysDescriptionAttribute	Obsolete. Marks a property, event, or extender with a description. Visual designers can display this description when referencing the member.
	DataTable	Represents one table of in-memory data.
	DataTableClearEventArgs	Provides data for the Clear method.
	DataTableCollection	Represents the collection of tables for the DataSet.
	DataTableExtensions	Defines the extension methods to the DataTable class. DataTableExtensions is a static class.
	DataTableNewRowEventArgs	Provides data for the NewRow method.
	DataTableReader	The DataTableReader obtains the contents of one or more DataTable objects in the form of one or more read-only, forward-only result sets.
	DataView	Represents a databindable, customized view of a DataTable for sorting, filtering, searching, editing, and navigation.
	DataViewManager	Contains a default DataViewSettingCollection for each DataTable in a DataSet.
	DataViewSetting	Represents the default settings for ApplyDefaultSort, DataViewManager, RowFilter, RowStateFilter, Sort, and Table for DataViews created from the DataViewManager.
	DataViewSettingCollection	Contains a read-only collection of DataViewSetting objects for each DataTable in a DataSet.
	DBConcurrencyException	The exception that is thrown by the DataAdapter during an insert, update, or delete operation if the number of rows affected equals zero.
	DeletedRowInaccessibleException	Represents the exception that is thrown when an action is tried on a DataRow that has been deleted.
	DuplicateNameException	Represents the exception that is thrown when a duplicate database object name is encountered during an add operation in a DataSet -related object.
	EntityCommandCompilationException	Represents errors that occur during command compilation; when a command tree could not be produced to represent the command text.
	EntityCommandExecutionException	Represents errors that occur when the underlying storage provider could not execute the specified command. This exception usually wraps a provider-specific exception.
	EntityException	Represents Entity Framework-related errors that occur in the EntityClient namespace. The EntityException is the base class for all Entity Framework exceptions thrown by the EntityClient.
	EntityKey	Provides a durable reference to an object that is an instance of an entity type.
	EntityKeyMember	Represents a key name and value pair that is part of an EntityKey.
	EntitySqlException	Represents errors that occur when parsing Entity SQL command text. This exception is thrown when syntactic or semantic rules are violated.
	EnumerableRowCollection	Represents a collection of DataRow objects returned from a LINQ to DataSet query. This API supports the .NET Framework infrastructure and is not intended to be used directly from your code.
	EnumerableRowCollection<(Of <(TRow>)>)	Represents a collection of DataRow objects returned from a query. This API supports the .NET Framework infrastructure and is not intended to be used directly from your code.
	EnumerableRowCollectionExtensions	Contains the extension methods for the data row collection classes. This API supports the .NET Framework infrastructure and is not intended to be used directly from your code.
	EvaluateException	Represents the exception that is thrown when the Expression property of a DataColumn cannot be evaluated.
	FillErrorEventArgs	Provides data for the FillError event of a DbDataAdapter.
	ForeignKeyConstraint	Represents an action restriction enforced on a set of columns in a primary key/foreign key relationship when a value or row is either deleted or updated.
	InRowChangingEventException	Represents the exception that is thrown when you call the EndEdit method within the RowChanging event.
	InternalDataCollectionBase	Provides the base functionality for creating collections.
	InvalidCommandTreeException	The exception that is thrown to indicate that a command tree is invalid.
	InvalidConstraintException	Represents the exception that is thrown when incorrectly trying to create or access a relation.
	InvalidExpressionException	Represents the exception that is thrown when you try to add a DataColumn that contains an invalid Expression to a DataColumnCollection.
	MappingException	The exception that is thrown when mapping related service requests fail.
	MergeFailedEventArgs	Occurs when a target and source DataRow have the same primary key value, and the EnforceConstraints property is set to true.
	MetadataException	The exception that is thrown when metadata related service requests fails.
	MissingPrimaryKeyException	Represents the exception that is thrown when you try to access a row in a table that has no primary key.
	NoNullAllowedException	Represents the exception that is thrown when you try to insert a null value into a column where AllowDBNull is set to false.
	ObjectNotFoundException	The exception that is thrown when an object is not present.
	OperationAbortedException	This exception is thrown when an ongoing operation is aborted by the user.
	OptimisticConcurrencyException	The exception that is thrown when an optimistic concurrency violation occurs.
	OrderedEnumerableRowCollection<(Of <(TRow>)>)	This API supports the .NET Framework infrastructure and is not intended to be used directly from your code. Represents a collection of ordered DataRow objects returned from a query.
	PropertyCollection	Represents a collection of properties that can be added to DataColumn, DataSet, or DataTable.
	ProviderIncompatibleException	The exception that is thrown when the underlying data provider is incompatible with the Entity Framework.
	ReadOnlyException	Represents the exception that is thrown when you try to change the value of a read-only column.
	RowNotInTableException	Represents the exception that is thrown when you try to perform an operation on a DataRow that is not in a DataTable.
	StateChangeEventArgs	Provides data for the state change event of a .NET Framework data provider.
	StatementCompletedEventArgs	Provides additional information for the StatementCompleted event.
	StrongTypingException	The exception that is thrown by a strongly typed DataSet when the user accesses a DBNull value.
	SyntaxErrorException	Represents the exception that is thrown when the Expression property of a DataColumn contains a syntax error.
	TypedDataSetGenerator	Obsolete. Used to create a strongly typed DataSet.
	TypedDataSetGeneratorException	The exception that is thrown when a name conflict occurs while generating a strongly typed DataSet.
	TypedTableBase<(Of <(T>)>)	This type is used as a base class for typed-DataTable object generation by Visual Studio and the XSD.exe .NET Framework tool, and is not intended to be used directly from your code.
	TypedTableBaseExtensions	Contains the extension methods for the TypedTableBase<(Of <(T>)>) class.
	UniqueConstraint	Represents a restriction on a set of columns in which all values must be unique.
	UpdateException	The exception that is thrown when modifications to object instances cannot be persisted to the data source.
	VersionNotFoundException	Represents the exception that is thrown when you try to return a version of a DataRow that has been deleted.

 Interfaces

	Interface	Description
	IColumnMapping	Associates a data source column with a DataSet column, and is implemented by the DataColumnMapping class, which is used in common by .NET Framework data providers.
	IColumnMappingCollection	Contains a collection of DataColumnMapping objects, and is implemented by the DataColumnMappingCollection, which is used in common by .NET Framework data providers.
	IDataAdapter	Allows an object to implement a DataAdapter, and represents a set of methods and mapping action-related properties that are used to fill and update a DataSet and update a data source.
	IDataParameter	Represents a parameter to a Command object, and optionally, its mapping to DataSet columns; and is implemented by .NET Framework data providers that access data sources.
	IDataParameterCollection	Collects all parameters relevant to a Command object and their mappings to DataSet columns, and is implemented by .NET Framework data providers that access data sources.
	IDataReader	Provides a means of reading one or more forward-only streams of result sets obtained by executing a command at a data source, and is implemented by .NET Framework data providers that access relational databases.
	IDataRecord	Provides access to the column values within each row for a DataReader, and is implemented by .NET Framework data providers that access relational databases.
	IDbCommand	Represents an SQL statement that is executed while connected to a data source, and is implemented by .NET Framework data providers that access relational databases.
	IDbConnection	Represents an open connection to a data source, and is implemented by .NET Framework data providers that access relational databases.
	IDbDataAdapter	Represents a set of command-related properties that are used to fill the DataSet and update a data source, and is implemented by .NET Framework data providers that access relational databases.
	IDbDataParameter	Used by the Visual Basic .NET Data Designers to represent a parameter to a Command object, and optionally, its mapping to DataSet columns.
	IDbTransaction	Represents a transaction to be performed at a data source, and is implemented by .NET Framework data providers that access relational databases.
	IExtendedDataRecord	Provides access to the column values within each row of a DbDataRecord for a DbDataReader.
	ITableMapping	Associates a source table with a table in a DataSet, and is implemented by the DataTableMapping class, which is used in common by .NET Framework data providers.
	ITableMappingCollection	Contains a collection of TableMapping objects, and is implemented by the DataTableMappingCollection, which is used in common by .NET Framework data providers.

 Delegates

	Delegate	Description
	DataColumnChangeEventHandler	Represents the method that will handle the ColumnChanging event.
	DataRowChangeEventHandler	Represents the method that will handle the RowChanging, RowChanged, RowDeleting, and RowDeleted events of a DataTable.
	DataTableClearEventHandler	Represents the method that handles the Clear method.
	DataTableNewRowEventHandler	Represents the method that handles the NewRow method.
	FillErrorEventHandler	Represents the method that will handle the FillError event.
	MergeFailedEventHandler	Represents the method that will handle the MergeFailed event.
	StateChangeEventHandler	Represents the method that will handle the StateChange event.
	StatementCompletedEventHandler	The delegate type for the event handlers of the StatementCompleted event.

 Enumerations

	Enumeration	Description
	AcceptRejectRule	Determines the action that occurs when the AcceptChanges or RejectChanges method is invoked on a DataTable with a ForeignKeyConstraint.
	CommandBehavior	Provides a description of the results of the query and its effect on the database.
	CommandType	Specifies how a command string is interpreted.
	ConflictOption	Specifies how conflicting changes to the data source will be detected and resolved.
	ConnectionState	Describes the current state of the connection to a data source.
	DataRowAction	Describes an action performed on a DataRow.
	DataRowState	Gets the state of a DataRow object.
	DataRowVersion	Describes the version of a DataRow.
	DataSetDateTime	Describes the serialization format for DateTime columns in a DataSet.
	DataViewRowState	Describes the version of data in a DataRow.
	DbType	Specifies the data type of a field, a property, or a Parameter object of a .NET Framework data provider.
	EntityState	The state of an entity object.
	IsolationLevel	Specifies the transaction locking behavior for the connection.
	KeyRestrictionBehavior	Identifies a list of connection string parameters identified by the KeyRestrictions property that are either allowed or not allowed.
	LoadOption	Controls how the values from the data source will be applied to existing rows when using the Load or Load method.
	MappingType	Specifies how a DataColumn is mapped.
	MissingMappingAction	Determines the action that occurs when a mapping is missing from a source table or a source column.
	MissingSchemaAction	Specifies the action to take when adding data to the DataSet and the required DataTable or DataColumn is missing.
	ParameterDirection	Specifies the type of a parameter within a query relative to the DataSet.
	PropertyAttributes	Obsolete. Specifies the attributes of a property.
	Rule	Indicates the action that occurs when a ForeignKeyConstraint is enforced.
	SchemaSerializationMode	Indicates the schema serialization mode for a typed DataSet.
	SchemaType	Specifies how to handle existing schema mappings when performing a FillSchema operation.
	SerializationFormat	Determines the serialization format for a DataSet.
	SqlDbType	Specifies SQL Server-specific data type of a field, property, for use in a SqlParameter.
	StatementType	Specifies the type of SQL query to be used by the OleDbRowUpdatedEventArgs, OleDbRowUpdatingEventArgs, SqlRowUpdatedEventArgs, or SqlRowUpdatingEventArgs class.
	UpdateRowSource	Specifies how query command results are applied to the row being updated.
	UpdateStatus	Specifies the action to take with regard to the current and remaining rows during an Update.
	XmlReadMode	Specifies how to read XML data and a relational schema into a DataSet.
	XmlWriteMode	Specifies how to write XML data and a relational schema from a DataSet.