System.Data Namespace

---

Represents an in-memory cache of data.

DataSet Class Members

Show Inherited Members

Constructors Visibility Constructor Parameters public DataSet ( ) public DataSet ( String dataSetName )   Properties Visibility Name Value Type Accessibility public CaseSensitive Boolean [ Get , Set ] public DataSetName String [ Get , Set ] public DefaultViewManager DataViewManager [ Get ] public EnforceConstraints Boolean [ Get , Set ] public ExtendedProperties PropertyCollection [ Get ] public HasErrors Boolean [ Get ] public IsInitialized Boolean [ Get ] public Locale CultureInfo [ Get , Set ] public Namespace String [ Get , Set ] public Prefix String [ Get , Set ] public Relations DataRelationCollection [ Get ] public RemotingFormat SerializationFormat [ Get , Set ] public SchemaSerializationMode SchemaSerializationMode [ Get , Set ] public Site ISite [ Get , Set ] public Tables DataTableCollection [ Get ]   Methods Visibility Name Parameters Return Type public AcceptChanges ( ) Void public BeginInit ( ) Void public Clear ( ) Void public Clone ( ) DataSet public Copy ( ) DataSet public CreateDataReader ( DataTable dataTables ) DataTableReader public CreateDataReader ( ) DataTableReader protected DetermineSchemaSerializationMode ( XmlReader reader ) SchemaSerializationMode protected DetermineSchemaSerializationMode ( SerializationInfo info , StreamingContext context ) SchemaSerializationMode public EndInit ( ) Void public GetChanges ( DataRowState rowStates ) DataSet public GetChanges ( ) DataSet public static GetDataSetSchema ( XmlSchemaSet schemaSet ) XmlSchemaComplexType public GetObjectData ( SerializationInfo info , StreamingContext context ) Void protected GetSchemaSerializable ( ) XmlSchema protected GetSerializationData ( SerializationInfo info , StreamingContext context ) Void public GetXml ( ) String public GetXmlSchema ( ) String public HasChanges ( DataRowState rowStates ) Boolean public HasChanges ( ) Boolean public InferXmlSchema ( TextReader reader , String nsArray ) Void public InferXmlSchema ( String fileName , String nsArray ) Void public InferXmlSchema ( XmlReader reader , String nsArray ) Void public InferXmlSchema ( Stream stream , String nsArray ) Void protected InitializeDerivedDataSet ( ) Void protected IsBinarySerialized ( SerializationInfo info , StreamingContext context ) Boolean public Load ( IDataReader reader , LoadOption loadOption , DataTable tables ) Void public Load ( IDataReader reader , LoadOption loadOption , String tables ) Void public Load ( IDataReader reader , LoadOption loadOption , FillErrorEventHandler errorHandler , DataTable tables ) Void public Merge ( DataRow rows , Boolean preserveChanges , MissingSchemaAction missingSchemaAction ) Void public Merge ( DataRow rows ) Void public Merge ( DataTable table , Boolean preserveChanges , MissingSchemaAction missingSchemaAction ) Void public Merge ( DataTable table ) Void public Merge ( DataSet dataSet , Boolean preserveChanges , MissingSchemaAction missingSchemaAction ) Void public Merge ( DataSet dataSet , Boolean preserveChanges ) Void public Merge ( DataSet dataSet ) Void protected OnPropertyChanging ( PropertyChangedEventArgs pcevent ) Void protected OnRemoveRelation ( DataRelation relation ) Void public ReadXml ( Stream stream , XmlReadMode mode ) XmlReadMode public ReadXml ( TextReader reader , XmlReadMode mode ) XmlReadMode public ReadXml ( String fileName , XmlReadMode mode ) XmlReadMode public ReadXml ( Stream stream ) XmlReadMode public ReadXml ( XmlReader reader ) XmlReadMode public ReadXml ( TextReader reader ) XmlReadMode public ReadXml ( XmlReader reader , XmlReadMode mode ) XmlReadMode public ReadXml ( String fileName ) XmlReadMode public ReadXmlSchema ( XmlReader reader ) Void public ReadXmlSchema ( Stream stream ) Void public ReadXmlSchema ( String fileName ) Void public ReadXmlSchema ( TextReader reader ) Void protected ReadXmlSerializable ( XmlReader reader ) Void public RejectChanges ( ) Void public Reset ( ) Void protected ShouldSerializeRelations ( ) Boolean protected ShouldSerializeTables ( ) Boolean public WriteXml ( XmlWriter writer ) Void public WriteXml ( String fileName ) Void public WriteXml ( Stream stream ) Void public WriteXml ( TextWriter writer ) Void public WriteXml ( XmlWriter writer , XmlWriteMode mode ) Void public WriteXml ( String fileName , XmlWriteMode mode ) Void public WriteXml ( Stream stream , XmlWriteMode mode ) Void public WriteXml ( TextWriter writer , XmlWriteMode mode ) Void public WriteXmlSchema ( Stream stream , Converter`2 multipleTargetConverter ) Void public WriteXmlSchema ( String fileName ) Void public WriteXmlSchema ( XmlWriter writer , Converter`2 multipleTargetConverter ) Void public WriteXmlSchema ( Stream stream ) Void public WriteXmlSchema ( TextWriter writer , Converter`2 multipleTargetConverter ) Void public WriteXmlSchema ( XmlWriter writer ) Void public WriteXmlSchema ( String fileName , Converter`2 multipleTargetConverter ) Void public WriteXmlSchema ( TextWriter writer ) Void   Events Multicast Name Type multicast Initialized EventHandler multicast MergeFailed MergeFailedEventHandler

The DataSet is an in-memory cache of data retrieved from a database, is a major component of the ADO.NET architecture. The DataSet consists of a collection of DataTable objects that you can relate to each other with DataRelation objects. You can also enforce data integrity in the DataSet by using the UniqueConstraint and ForeignKeyConstraint objects. For further details about working with DataSet objects, see Creating and Using DataSets.

While DataTable objects contain the data, the DataRelationCollection allows you to navigate though the table hierarchy. The tables are contained in a DataTableCollection accessed through the Tables property. When accessing DataTable objects, note that they are conditionally case-sensitive. For example, if one DataTable is named "mydatatable" and another is named "myDataTable", a string used to search for one of the tables is regarded as case-sensitive. However, if "mydatatable" exists and "myDataTable" does not, the search string is regarded as case-insensitive. For more information about working with DataTable objects, see Creating a DataTable.

A DataSet reads and writes data and schema as XML documents. The data and schema can be transported across HTTP and used by any application, on any platform that is XML-enabled. You can save the schema as an XML schema with the WriteXmlSchema method, and the schema and data can be saved using the WriteXml method. If you need to read an XML document that includes both schema and data, use the ReadXml method which infers and initializes a schema from the document.

In a typical multiple-tier implementation, the steps for creating and refreshing a DataSet, and in turn, updating the original data shouce would be to:

1. Build and fill each DataTable in a DataSet with data from a data source using an SqlDataAdapter or OleDbDataAdapter.
2. Change the data in individual DataTable objects by adding, updating, or deleting DataRow objects.
3. Invoke the GetChanges method to create a second DataSet that features only the changes to the data.
4. Check for errors in the second DataSet by examining its HasErrors property which informs you if any table in the set has errors.
5. If errors are present, check the HasErrors property of each DataTable. If the DataTable contains errors, call the GetErrors method of the DataTable object to return an array of DataRow objects containing errors.
6. On each DataRow, examine the RowError property for specific data. .
7. Invoke the Merge method to merge the changes from the second DataSet into the first.
8. Call the Update method of the SqlDataAdapter ( or OleDbDataAdapter ), passing the merged DataSet as an argument.
9. Invoke the AcceptChanges on the DataSet. Alternatively, invoke RejectChanges to cancel the changes.

CAUTION: the DataSet stores data using the set of .NET Framework types. This is generally the most convenient representation for the user, but may cause problems when the back-end type is an SQL Server™ decimal data type. The .NET Framework decimal type allows a maximum of 28 significant digits, while the SQL Server™ decimal data type allows 38 significant digits. If an application attempts to fill a .NET Framework decimal data type with an SQL Server™ decimal data type, an exception is thrown and the fill operation terminates because data cached in the DataSet would lose the extra precision.

NOTE: the DataSet and DataTable objects inherit from MarshalByValueComponent, and support the ISerializable interface for remoting. These are the only ADO.NET objects that can be remoted.

The following example demonstrates using a DataAdapter to retrieve SQL Server™ data into a Dataset, then iterate thru and display the contents of the DataSet using simple foreach loops.

 Show me 

See Retrieving Data Using a DataSet for related information.

The below example demonstrates using ReadXml to load an XML file into a Dataset, then iterates thru and displays the contents of the DataSet using simple foreach loops.

 Show me 

See Retrieving XML Data Using a DataSet for related information.

DataTable   DataRelation   DataRow   DataView   ForeignKeyConstraint   OleDbDataAdapter   SqlDataAdapter   UniqueConstraint

Suggested Reading