Tài liệu The ForeignKeyConstraint Class pdf

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.