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Path Expressions

  1. An expression of the form ``'' is called a path-expression. References can be used to hide join operations and thus the use of references simplifies the query considerably.
  2. Example.

    		 create table phd-students

    (advisor (ref(people))

    under people


    from phd-students

  3. In general, attributes used in a path expression can be a collection, such as a set or a multiset. E.g., to get names of all authors of documents, we have


    from as Y

Osmar Zaiane
Tue Jul 7 15:03:55 PDT 1998