Real Time Information Director User Documentation

RTID Metadata Language
Hewlett-Packard Company 16 529618-002
DependentLinks
You use DependentLinks, rather than Links, when a record is linked to the parent by a
different criterion than was used to select the parent records. For example, as long as all
the tables in an order document are related by order number, there is no need for
DependentLinks. The need arises in a case like the record for a product; such a record
will not have an order number, because many orders can refer to the same product. To a
link a product record into the order document, you must introduce a dependent link on the
product number specified in the parent order line detail.
Whereas the Links class correlates one or more linking columns in a child record with
key columns in the parent record, the DependentLinks class correlates linking fields in
the child record with fields that are not necessarily keys in the parent record.
DependentLinks causes the Director to perform multiple SELECT statements to get the
set of linked records. (In contrast, all child records connected to the parent by a Links
object can be selected in a single statement.)
DependentLinks is a subclass of Links, has the same parameters as Links, and can be
passed, in place of Links, to any constructor that supports a Links parameter.
For specifics of the syntax, see the Javadoc for DependentLinks.
The branch library example uses dependent links in numerous document definitions.
Here is a visual representation of some of the major objects used by the example: