The DataSet and Related Classes

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Sams Teach Yourself ASP.NET in 21 Days, Second Edition
By Chris Payne
Table of Contents
Appendix D.  ADO.NET Controls: Properties and Methods


The DataSet and Related Classes

The following are the details for the DataSet and related items, such as DataRelation, DataTable, and so on.

Constraint and ConstraintCollection

This Constraint class represents a rule on a table that limits the data that can be modified. Table C.1 lists the properties of the Constraint class.

Table C.1. Properties of the Constraint Class
Property Description
ConstraintName The name of this constraint.
ExtendedProperties Retrieves a collection of user-defined properties.
Table Returns DataTable to which this constraint applies.

Table C.2 lists the property, methods, and event of the ConstraintCollection class.

Table C.2. Property, Methods, and Event of the ConstraintCollection Class
Property Description
Item Gets a constraint in the collection with either the name of the constraint or its index in the collection.
Method Description
Add Adds a constraint to the collection. This method is overloaded. See the .NET Framework SDK documentation for more information.
AddRange Copies the elements from another ConstraintCollection object into the current one.
CanRemove Indicates if a constraint specified by Constraint can be removed from the DataTable.
Clear Clears the collection of all Constraint objects.
Contains Indicates if the Constraint with the name name exists in the collection.
IndexOf Retrieves the index of the specified constraint. This method is overloaded. See the .NET Framework SDK documentation for more information.
Remove Removes the specified constraint from the collection. This method is overloaded. See the .NET Framework SDK documentation for more information.
RemoveAt Removes the Constraint at the specified index.
Event Description
CollectionChanged Occurs when the collection is changed through additions or removals. Uses a CollectionChangeEventArgs object for the event parameter. This object contains the following properties:

Action? Returns a value (Add, Remove, Refresh) indicating how the collection has changed.

Element? Returns the instance of the collection that changed.

DataColumn and DataColumnCollection

A DataColumn represents a column of information in a DataTable. Table C.3 lists the properties and method of the DataColumn class.

Table C.3. Properties and Method of the DataColumn Class
Property Description
AllowDBNull Indicates if null values are allowed in this column.
AutoIncrement Indicates if the value of the column automatically increments with the addition of a new row.
AutoIncrementSeed The starting value for AutoIncrement
AutoIncrementStep The increment value used by AutoIncrement.
Caption The caption for this column.
ColumnMapping Returns a MappingType object indicating how the column is mapped when written as XML.
ColumnName The name of the column.
DataType The type of data stored in this column.
DefaultValue The default value for this column when creating new rows.
Expression A string expression used to filter rows, calculate the column's value, or create an aggregate column.
ExtendedProperties Returns a PropertyCollection of custom user information.
MaxLength The maximum length of a text column.
Namespace The XML namespace containing the elements used in this column.
Ordinal The position of this column in the DataColumnCollection.
Prefix The prefix used for this column when represented as XML.
ReadOnly Indicates if the column allows changes.
Table Returns DataTable to which this column belongs.
Unique Indicates if each value in the column must be unique.
Method Description
ToString Returns the Expression of this column, if one exists.

Table C.4 lists the property, methods, and event of the DataColumnCollection class.

Table C.4. Property, Methods, and Event of the DataColumnCollection Class
Property Description
Item Gets a DataColumn in the collection with either the name of the column or its index in the collection.
Method Description
Add Adds a column to the collection. This method is overloaded. See the .NET Framework SDK documentation for more information.
AddRange Adds an array of DataColumn objects to the collection.
CanRemove Indicates if a column specified by Column can be removed from the collection.
Clear Clears the collection of all DataColumn objects.
Contains Indicates if the DataColumn with the name name exists in the collection.
IndexOf Retrieves the index of the specified column. This method is overloaded. See the .NET Framework SDK documentation for more information.
Remove Removes the specified column from the collection. This method is overloaded. See the .NET Framework SDK documentation for more information.
RemoveAt Removes the DataColumn at the specified index.
Event Description
CollectionChanged Occurs when the collection is changed through additions or removals. Uses a CollectionChangeEventArgs object for the event parameter. This object contains the following properties:

Action? Returns a value (Add, Remove, Refresh) indicating how the collection has changed.

Element? Returns the instance of the collection that changed.

DataRelation and DataRelationCollection

A DataRelation class represents the relationship between multiple tables in the DataSet. Table C.5 lists the properties of the DataRelation class.

Table C.5. Properties of the DataRelation Class
Property Description
ChildColumns Returns an array of DataColumn objects that represent the child columns of this relation.
ChildKeyConstraint A ForeignKeyConstraint object for this relation.
ChildTable Returns a DataTable representing the child table of this relation.
DataSet Returns the DataSet to which this relation belongs to.
ExtendedProperties Returns a PropertyCollection of custom user information.
Nested Indicates if relations are nested.
ParentColumns An array of DataColumn objects that represent the parent columns of this relation.
ParentKeyConstraint A UniqueConstraint object for this relation.
ParentTable Returns the DataTable representing the parent table of this relation.
RelationName The name of this relation.

Table C.6 lists the property, methods, and event of the DataRelationCollection class.

Table C.6. Property, Methods, and Event of the DataRelationCollection Class
Property Description
Item Gets a DataRelation in the collection with either the name of the relation or its index in the collection.
Method Description
Add Adds a relation to the collection. This method is overloaded. See the .NET Framework SDK Documentation for more information.
AddRange Adds an array of DataRelation objects to the collection.
CanRemove Verifies whether the specified DataRelation can be removed from the collection.
Clear Clears the collection of all DataRelationobjects.
Contains Indicates if the DataRelation with the name name exists in the collection.
IndexOf Returns the index of the specified DataRelation.
Remove Removes the specified relation from the collection. This method is overloaded. See the .NET Framework SDK Documentation for more information.
RemoveAt Removes the DataRelation at the specified index.
CollectionChanged Occurs when the collection is changed through additions or removals. Uses a CollectionChangeEventArgs object for the event parameter. This object contains the following properties:

Action? Returns a value (Add, Remove, Refresh) indicating how the collection has changed.

Element? Returns the instance of the collection that changed.

DataRow and DataRowCollection

A DataRow represents a row of information in a DataTable, that is, an individual record of data. Table C.7 lists the properties and methods of the DataRow class.

Table C.7. Properties and Methods of the DataRow Class
Property Description
HasErrors Indicates if the data in the row contains any errors.
Item Specifies the data contained in the specified column. The method is overloaded. See the .NET Framework SDK documentation for more details.
ItemArray Specifies the data contained in the entire row, through an array.
RowError The custom error description for the row.
RowState The state of the row. Can be Detached, Unchanged, New, Deleted, or Modified.
Table Returns DataTable to which this row belongs.
Method Description
AcceptChanges Commits all changes made to the row.
BeginEdit Begins an edit operation on the row.
CancelEdit Cancels an edit operation, repealing edits.
ClearErrors Clears all errors for the row.
Delete Deletes the row.
EndEdit Ends the edit operation on the row.
GetChildRows Returns an array of DataRow objects representing the child rows of this row, when using the specified DataRelation.
GetColumnError Gets the error for a specified column in the row. This method is overloaded. See the .NET Framework SDK documentation for more information.
GetColumnsInError Gets an array of DataColumn objects that have errors.
GetParentRow Returns a DataRow representing the parent of this row. This method is overloaded. See the .NET Framework SDK documentation for more details.
GetParentRows Returns an array of DataRow objects representing the parent of this row using the specified DataRelation. This method is overloaded. See the .NET Framework SDK documentation for more details.
HasVersion Indicates if a specified version of the row exists.
IsNull Indicates if the specified column in the row contains a null value. This method is overloaded. See the .NET Framework SDK documentation for more details.
RejectChanges Rolls back all changes made to the row.
SetColumnError Sets the error description for the column. This method is overloaded.
SetParentRow Sets the parent row of a given child row. This method is overloaded.

Table C.8 lists the property and methods of the DataRowCollection class.

Table C.8. Property and Methods of the DataRowCollection Class
Property Description
Item Gets a DataRow in the collection with either the name of the row or its index in the collection.
Method Description
Add Adds a row to the collection. This method is overloaded.
Clear Clears the collection of all DataRow objects.
Contains Indicates if the DataRow with the name name exists in the collection.
Find Gets a specified DataRow. This method is overloaded.
InsertAt Inserts a new DataRow at the specified location.
Remove Removes the specified row from the collection. This method is overloaded.
RemoveAt Removes the DataRow at the specified index.

DataSet

Table C.9 lists the properties, methods, and event of the DataSet class, which represents a disconnected data source.

Table C.9. Properties, Methods, and Event of the DataSet Class
Property Description
CaseSensitive Indicates if string comparisons in a DataTable are case-sensitive.
DataSetName The name of this DataSet.
DefaultViewManager Returns a DataViewManager that contains a customized view of the data in the DataSet.
EnforceConstraints Indicates if constraint rules are followed when updating the data.
ExtendedProperties A PropertyCollection object containing custom user information.
HasErrors Indicates if the data in any of the rows of this DataSet contain errors.
Locale The locale information used to compare strings. Returns a CultureInfo object.
Namespace Indicates the namespace of the DataSet.
Prefix An XML alias for the namespace of the DataSet.
Relations A DataRelationCollection object that represents all relations between tables in the DataSet.
Site Returns an ISite interface for the DataSet (used to bind components to containers).
Tables A DataTableCollection object representing all tables in the DataSet.
Method Description
AcceptChanges Commits all changes made to the DataSet.
Clear Removes all rows in all tables in the DataSet.
Clone Produces a DataSet identical to the current DataSet, without data.
Copy Produces a DataSet identical to the current DataSet, with data.
GetChanges Produces a DataSet that contains only the data that has changed.
GetXml Returns the data in the DataSet in XML format.
GetXmlSchema Returns the XML schema for the data in the DataSet.
HasChanges Indicates if the data in the DataSet has changed at all.
InferXmlSchema Builds the data structure from an XML data source. This function is overloaded; see the .NET SDK documentation for more details.
Merge Merges the specified DataSet with the one specified.
ReadXml Inserts data and schema information from an XML file in a DataSet.
ReadXmlSchema Builds the data structure from an XML schema. This function is overloaded; see the .NET SDK documentation for more details.
RejectChanges Undoes all changes that have been made to this DataSet.
Reset Resets the DataSet to its default properties.
WriteXml Writes the content of the DataSet in XML format. This function is overloaded; see the .NET SDK documentation for more details.
WriteXmlSchema Writes the structure of the DataSet in XML format. This function is overloaded; see the .NET SDK Documentation for more details.
Event Description
MergeFailed Occurs when a target and source DataRow have the same primary key value, and EnforceConstraints is true.

DataTable and DataTableCollection

A DataTable represents a table of information in a DataSet. Table C.10 lists the properties, methods, and events of the DataTable class.

Table C.10. Properties, Methods, and Events of the DataTable Class
Property Description
CaseSensitive Indicates if string comparisons in the table are case-sensitive.
ChildRelations Returns a DataRelationCollection of the child relations of this table.
Columns Returns a DataColumnCollection object representing the column in this table.
Constraints Returns a DataRelationCollection object representing the data relations in this table.
DataSet Returns the DataSet this table belongs to.
DefaultView Returns a DataView representing a customized view of the data in this table.
DisplayExpression A string expression that returns a value indicating how to display this table in the UI.
ExtendedProperties Returns a PropertyCollection of custom user information.
HasErrors Indicates if there are any errors in any of the rows of this table.
Locale A CultureInfo object used to determine how strings are compared.
MinimumCapacity The initial starting size for this table.
Namespace The XML namespace containing the elements used in this table.
ParentRelations A DataRelationCollection of the parent relations of this table.
Prefix The prefix used for this table when represented as XML.
PrimaryKey An array of DataColumn objects that serve as the primary keys of the table.
Rows A DataRowCollection object representing the rows belonging to this table.
Site Returns an ISite interface for the DataTable (used to bind components to containers).
TableName The name of the table.
Method Description
AcceptChanges Commits all changes made to this table.
BeginInit Begins the initialization of this table.
BeginLoadData Begins the data loading process.
Clear Clears the table of all data.
Clone Makes a copy of the DataTable's structure, including all its relations.
Compute Computes the expression specified in the first parameter on the rows that pass the specified filter.
Copy Copies both the structure and data contained in the DataTable.
EndInit Ends the initialization process.
EndLoadData Ends the data loading process.
GetChanges Gets a copy of the DataTable that contains only the changes made to it since it was first created, or since AcceptChanges was called.
GetErrors An array of DataRow objects that contain errors.
ImportRow Copies a DataRow object into the DataTable.
LoadDataRow Finds and updates a DataRow with the specified values. If a row is not found, a new one is created.
NewRow Returns a blank DataRow with the same schema as the table.
RejectChanges Rolls back all changes made to the table since it was first loaded or since AcceptChanges was last called.
Reset Resets the DataTable to its default properties.
Select Returns an array of DataRow objects. This method is overloaded.
ToString Returns the TableName and DisplayExpression of this table.
Event Description
ColumnChanged Occurs when a column has changed. Uses a DataColumnChangedEventArgs object for the event parameter. This object contains the following properties:

Column? The column that changed. ProposedValue The value to change to column to.

Row? The DataRow to change.

ColumnChanging Occurs when changes have been submitted for this column. Uses a DataColumnChangedEventArgs object.
RowChanged Occurs when a row has changed. Uses a DataRowChangedEventArgs object for the event parameter. This object contains the following properties:

Action? The action that occurred on the DataRow.

Row? Thse DataRow to change.

RowChanging Occurs when changes have been submitted for this column. Uses a DataRowChangedEventArgs object.
RowDeleted Occurs after a row is deleted. Uses a DataRowChangedEventArgs object.
RowDeleting Occurs before a row is deleted. Uses a DataRowChangedEventArgs object.

Table C.11 lists the property, methods, and events of the DataTableCollection class.

Table C.11. Property, Methods, and Events of the DataTableCollection Class
Property Description
Item Gets a DataTable in the collection with either the name of the table or its index in the collection.
Methods Description
Add Adds a table to the collection. This method is overloaded.
AddRange Adds an array of DataTable objects to the collection.
CanRemove Indicates if the table specified can be removed from the collection.
Clear Clears the collection of all DataTable objects.
Contains Indicates if the DataTable with the specified name exists in the collection.
IndexOf Retrieves the index of the specified table. This method is overloaded.
Remove Removes the specified table from the collection. This method is overloaded.
RemoveAt Removes the DataTable at the specified index.
Event Description
CollectionChanged Occurs when the collection is changed through additions or removals. Uses a CollectionChangeEventArgs object for the event parameter. This object contains the following properties:

Action? Returns a value (Add, Remove, Refresh) indicating how the collection has changed.

Element? Returns the instance of the collection that changed.

CollectionChanging Occurs before the collection is changed. Uses a CollectionChangeEventArgs object.

DataView

A DataView class represents a customized view of the data in a DataSet. Table C.12 lists the properties, methods, and event of the DataView class.

Table C.12. Properties, Methods, and Event of the DataView Class
Property Description
AllowDelete Indicates if deletes are allowed in this view.
AllowEdit Indicates if edit are allowed in this view.
AllowNew Indicates if new rows can be added in this view.
ApplyDefaultSort Indicates if the default sort should be used.
Count Returns the number of records in the DataView.
DataViewManager The DataView that created this view (a pointer to the DataSetView that owns the corresponding DataSet).
Item Gets a specified row of data from a table.
RowFilter An expression used to filter which rows are added to the DataView.
RowStateFilter Specifies which version of rows is added to the DataView. Can be None, Unchanged, New, Deleted, ModifiedCurrent, ModifiedOriginal, OriginalRows, and CurrentRows (default).
Sort The columns to sort by.
Table The source DataTable from which to pull data.
Methods Description
AddNew Adds a new row to the DataView.
BeginInit Begins the initialization of this DataView.
CopyTo Copies items into an array.
Delete Deletes a row at the specified index.
EndInit Ends the initialization process.
Find Finds a specified row in the DataView. This method is overloaded.
FindRows Returns an array of DataRowView objects that match the specified criteria.
GetEnumerator Returns an IEnumerator that can be used to iterate through this DataView.
Event Description
ListChanged Occurs when the list managed by the DataView changes. Uses a ListChangedEventArgs object for the event parameter. This object contains the following properties:

ListChangedType? The way the list changed. NewIndex The new index of the item that changed.

OldIndex? The old index of the item that changed.


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    Sams Teach Yourself ASP. NET in 21 Days
    Sams Teach Yourself ASP.NET in 21 Days (2nd Edition)
    ISBN: 0672324458
    EAN: 2147483647
    Year: 2003
    Pages: 307
    Authors: Chris Payne

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