The ADO.Net DataSet Object Part 2

 

DataRow Class Members

Properties Visibility Name Value Type Accessibility         public HasErrors Boolean [ Get ]         public Item ( Int32 columnIndex ) ( DataRowVersion version ) Object [ Get ]         public Item ( DataColumn column ) Object [ Get , Set ]         public Item ( DataColumn column ) ( DataRowVersion version ) Object [ Get ]         public Item ( String columnName ) ( DataRowVersion version ) Object [ Get ]         public Item ( Int32 columnIndex ) Object [ Get , Set ]         public Item ( String columnName ) Object [ Get , Set ]         public ItemArray Object [ Get , Set ]         public RowError String [ Get , Set ]         public RowState DataRowState [ Get ]         public Table DataTable [ Get ]           Methods February 11, 2008 Visibility Name Parameters Return Type         public AcceptChanges ( ) Void         public BeginEdit ( ) Void         public CancelEdit ( ) Void         public ClearErrors ( ) Void         public Delete ( ) Void         public EndEdit ( ) Void         public GetChildRows ( String relationName ) DataRow         public GetChildRows ( String relationName , DataRowVersion version ) DataRow         public GetChildRows ( DataRelation relation , DataRowVersion version ) DataRow       public GetChildRows ( DataRelation relation ) DataRow         public GetColumnError ( Int32 columnIndex ) String         public GetColumnError ( String columnName ) String         public GetColumnError ( DataColumn column ) String         public GetColumnsInError ( ) DataColumn         public GetParentRow ( String relationName , DataRowVersion version ) DataRow         public GetParentRow ( String relationName ) DataRow         public GetParentRow ( DataRelation relation , DataRowVersion version ) DataRow         public GetParentRow ( DataRelation relation ) DataRow         public GetParentRows ( DataRelation relation , DataRowVersion version ) DataRow         public GetParentRows ( DataRelation relation ) DataRow         public GetParentRows ( String relationName , DataRowVersion version ) DataRow         public GetParentRows ( String relationName ) DataRow         public HasVersion ( DataRowVersion version ) Boolean         public IsNull ( String columnName ) Boolean         public IsNull ( DataColumn column , DataRowVersion version ) Boolean         public IsNull ( DataColumn column ) Boolean         public IsNull ( Int32 columnIndex ) Boolean         public RejectChanges ( ) Void         public SetColumnError ( Int32 columnIndex , String error ) Void         public SetColumnError ( DataColumn column , String error ) Void         public SetColumnError ( String columnName , String error ) Void         public SetParentRow ( DataRow parentRow , DataRelation relation ) Void         public SetParentRow ( DataRow parentRow )

The DataSet is a much more powerful and complicated object than the DataReader. The DataReader is a read-only forward-only object wherein once a record is read it is gone, unless it is saved into an array. The DataSet and DataTable objects are virtualls datasets and tables which are used in client-side operations. Though there is no ‘current record’ concept, the user is able to navigate between the rows using loops, either using the Rows collection of the DataTable object, or the DataRow object.

 

For i=1 to 3

tblEmployee.Rows(i)(“FirstName”)=”Daffy”

or

dim dr as DataRow=tblEmployee.Rows(i)

dr(“LastName”)=”Duck”

Next

Don’t forget that the DataSet is disconnected from the original server-side source of the data. So any changes in the DataSet will not be reflected in the source unless and until the DataSet and the Source are reconciled. You can find the status of any record by querying the RowState property of the DataRow object. The result will be one of the following: Detached, Added, Modified, Deleted, or Unchanged. Though the RowState property is read only, the DataRow has two properties which can change it: the AcceptChanges, and RejectChanges Properties.

Of further note are the DataTable.ColumnChanging, the DataTable.ColumnChanged, the DataTable.RowChanging, and the DataTable.RowChanged events which allow you to trap and code for these events within your code.

The DataView Object

The function of the DataView object is to facilitate data binding of data to Windows forms and web pages. Additionally, it can be used along with the Select method od the DataTable Object to present subsets of records from tables. Use the RowFilter property to select which records are visible, and use the Sort property to order their presentation.

 

DataView Class Members

Constructors Visibility Constructor Parameters       public DataView ( )       public DataView ( DataTable table )       public DataView ( DataTable table , String RowFilter , String Sort , DataViewRowState RowState )       Properties Visibility Name Value Type Accessibility         public AllowDelete Boolean [ Get , Set ]         public AllowEdit Boolean [ Get , Set ]         public AllowNew Boolean [ Get , Set ]         public ApplyDefaultSort Boolean [ Get , Set ]         public Container IContainer [ Get ]         public Count Int32 [ Get ]         public DataViewManager DataViewManager [ Get ]         public DesignMode Boolean [ Get ]         public Item ( Int32 recordIndex ) DataRowView [ Get ]         public RowFilter String [ Get , Set ]         public RowStateFilter DataViewRowState [ Get , Set ]         public Site ISite [ Get , Set ]         public Sort String [ Get , Set ]         public Table DataTable [ Get , Set ]         Methods Visibility Name Parameters Return Type         public AddNew ( ) DataRowView         public BeginInit ( ) Void         public CopyTo ( Array array , Int32 index ) Void         public Delete ( Int32 index ) Void         public EndInit ( ) Void         public Find ( Object key ) Int32         public Find ( Object key ) Int32         public FindRows ( Object key ) DataRowView         public FindRows ( Object key ) DataRowView         public GetEnumerator ( ) IEnumerator         Events Multicast Name Type       multicast Disposed EventHandler       multicast ListChanged ListChangedEventHandler

 

Resources

• Tutorial: Filtering Dataset Results

This is a useful tutorial that discusses sorting out Dataset results.

• Information: Properties of files and Datasets

This resource throws light on Properties of files and Datasets.