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System.Data Namespace

The System.Data namespace consists mostly of the classes that constitute the ADO.NET architecture. The ADO.NET architecture enables you to build components that efficiently manage data from multiple data sources. 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 allow you to further ensure data integrity. The Expression property enables you to 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 DataSet object's DataRelationCollection. 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 ensures that values 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), or the System.Data.OleDb namespace (the .NET Framework Data Provider for OLE DB), you can access a data source to use in conjunction with a DataSet. Each .NET data provider has a corresponding DataAdapter that you use as a bridge between a data source and a DataSet.

Namespace hierarchy

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.
DataRowChangeEventArgs Provides data for the RowChanged, RowChanging, OnRowDeleting, and OnRowDeleted events.
DataRowCollection Represents a collection of rows for a DataTable.
DataRowView Represents a customized view of a DataRow exposed as a fully featured Windows Forms control.
DataSet Represents an in-memory cache of data.
DataSysDescriptionAttribute 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.
DataTableCollection Represents the collection of tables for the DataSet.
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 the update operation if the number of rows affected equals zero.
DeletedRowInaccessibleException Represents the exception that is thrown when an action is attempted 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.
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 calling the EndEdit method within the RowChanging event.
InternalDataCollectionBase Provides the base functionality for creating collections.
InvalidConstraintException Represents the exception that is thrown when incorrectly attempting to create or access a relation.
InvalidExpressionException Represents the exception that is thrown when attempting to add a DataColumn containing an invalid Expression to a DataColumnCollection.
MergeFailedEventArgs Occurs when a target and source DataRow have the same primary key value, and the EnforceConstraints property is set to true.
MissingPrimaryKeyException Represents the exception that is thrown when attempting to access a row in a table that has no primary key.
NoNullAllowedException Represents the exception that is thrown when attempting to insert a null value into a column where AllowDBNull is set to false.
PropertyCollection Represents a collection of properties that can be added to DataColumn, DataSet, or DataTable.
ReadOnlyException Represents the exception that is thrown when attempting to change the value of a read-only column.
RowNotInTableException Represents the exception that is thrown when trying 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.
StrongTypingException The exception that is thrown by a strongly-typed DataSet when the user accesses DBNull value.
SyntaxErrorException Represents the exception that is thrown when the Expression property of a DataColumn contains a syntax error.
TypedDataSetGenerator Used to create a strongly-typed DataSet.
TypedDataSetGeneratorException The exception that is thrown when a name conflict occurs while generating a strongly-typed DataSet.
UniqueConstraint Represents a restriction on a set of columns in which all values must be unique.
VersionNotFoundException Represents the exception that is thrown when attempting 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 used to fill and refresh 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.
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.
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.

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.
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.
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.
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.
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 Specifies the attributes of a property.
Rule Indicates the action that occurs when a ForeignKeyConstraint is enforced.
SchemaType Specifies how to handle existing schema mappings when performing a FillSchema operation.
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.

See Also

.NET Framework Class Library

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