DataRelation
objects are contained in a DataRelationCollection
.
Every DataSet
exposes a
DataRelationCollection
through its
Relations
property. In addition, you can access
the DataRelation
objects that pertain to a
specific table through the
DataTable.ChildRelations
and
DataTable.ParentRelations
properties.
The DataRelation
links two matching
DataColumn
objects from different tables. Thus,
the data type of both columns must be identical. When a
DataRelation
object is created, the relationship
is verified. Once you add the DataRelation
to the
DataSet.Relations
collection, a
ForeignKeyConstraint
is generated for the child
table, preventing changes that would violate relational integrity.
The following code creates and adds a DataRelation
:
DataColumn parentCol = ds.Tables["Categories"].Columns["CategoryID"]; DataColumn childCol = ds.Tables["Products"].Columns["CategoryID"]; DataRelation dr = new DataRelation("Cat_Prod", parentCol, childCol); ds.Relations.Add(dr);