The ForeignKeyConstraint Class

The ForeignKeyConstraint Class

You use an object of the ForeignKeyConstraint class to represent a foreign key constraint between two DataTable objects. This ensures that each DataRow in your child DataTable has a matching DataRow in your parent DataTable. The ForeignKeyConstraint class is derived from the System.Data.Constraint class. Table 12.2 shows the ForeignKeyConstraint properties.

Table 12.2: ForeignKeyConstraint PROPERTIES

PROPERTY

TYPE

DESCRIPTION

AcceptRejectRule

AcceptRejectRule

Gets or sets the AcceptRejectRule that indicates the action that is to take place when the AcceptChanges() method of the DataTable is called.

The members of the System.Data.AcceptRejectRule enumeration are

  • Cascade, which indicates that the changes to the DataRow objects in the parent DataTable are also made in the child DataTable.

  • None, which indicates that no action takes place.

The default is None.

Columns

DataColumn[]

Gets the array of DataColumn objects from the child DataTable.

ConstraintName

string

Gets the name of the UniqueConstraint object.

DeleteRule

Rule

Gets or sets the Rule that indicates the action that is to take place when a DataRow in the parent DataTable is deleted.

The members of the System.Data.Rule enumeration are

  • Cascade, which indicates that the delete or update to the DataRow objects in the parent DataTable is also made in the child DataTable.

  • None, which indicates that no action takes place.

  • SetDefault, which indicates that the DataColumn values in the child DataTable are to be set to the value in the DefaultValue property of the DataColumn.

  • SetNull, which indicates that the DataColumn values in the child DataTable are to be set to DBNull.

The default is Cascade.

ExtendedProperties

PropertyCollection

Gets the PropertyCollection object that you can use to store strings of additional information.

RelatedColumns

DataColumn[]

Gets the array of DataColumn objects in the parent DataTable for the UniqueConstraint.

RelatedTable

DataTable

Gets the parent DataTable for the UniqueConstraint.

Table

DataTable

Gets the child DataTable to which the UniqueConstraint belongs.

UpdateRule

Rule

Gets or sets the Rule that indicates the action that is to take place when a DataRow in the parent DataTable is updated. See the DeleteRule property for the members of the Rule enumeration.

The default is Cascade.




Mastering C# Database Programming
Mastering the SAP Business Information Warehouse: Leveraging the Business Intelligence Capabilities of SAP NetWeaver
ISBN: 0764596373
EAN: 2147483647
Year: 2003
Pages: 181

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