Adding and Removing Relations
Relations belonging to the DataSet
are stored as
DataRelation
objects in a
DataRelationCollection
object and are accessed
through the Relations
property of the
DataSet
. Each DataRelation
object represents the relationship between a parent and child table
in the DataSet
. This section examines some methods
and properties of the
DataRelationCollection
.
Relations are added to the DataSet
using the
Add( )
method of the
DataRelationCollection
, as shown in the following
example:
ds.Relations.Add("MyDataRelation", parentTable.Columns["PrimaryKeyField"], childTable.Columns["ForeignKeyField"]);
The Remove( )
method removes a relation matching the relation-name argument. The
following example removes the relation added in the previous example:
ds.Relations.Remove("MyDataRelation");
The Contains( )
method can determine if a
specific relation exists as shown in the following example:
Boolean exists = ds.Relations.Contains("MyRelation");
Relations and the DataRelationCollection
are
discussed in detail in Chapter 11.
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