<das:foreign-key> describes a foreign key constraint from the current table to its parents.
Attributes:
id - unique identifier of this resource in the current processing job.
parent-key - the name of the field in the referenced table.
key - the name of the field in the referencing table.
parent-id - the referenced data-source id. Must be a table data source.
Note. A comprehensive sample using foreign-keys can be found in Job Samples folder.
<das:foreign-key id="fkey" parent-key="ID" key="EMP_ID" parent-id="ds1"/>