Version 4 (modified by Dominic König, 10 years ago) ( diff )



Table of Contents

  1. Purpose
  2. Example
  3. Data Model


The S3Hierarchy toolkit can be used to perform lookups in hierarchical taxonomies. It analyses the parent-relationships of the records, and provides methods to access and search through the parent-, child- and sibling-axes of each record.


Facility type as an example for a hierarchical taxonomy:

  • Arts and Recreation
    • Recreation Centers
  • Community Groups
    • Volunteer Opportunities
  • Education
    • Adult Education
    • Guidance and Tutoring Programs
  • Health and Mental Health
    • Dental Care
    • Health Centers
    • Health Clinics
    • Health Screening and Testing
    • Hospitals and Medical Centers
    • Mental Health Counseling
    • Mental Health Programs
    • Public Health Programs
    • Substance Abuse Programs
  • Social Services
    • Children and Family Services
    • Public Information Services
    • Senior Services
    • Support Groups

Data Model

To store a hierarchical taxonomy, the database table must include a parent reference (self-reference).

This can either be a foreign key to the table, or - if the table is a super-entity instance - a (second) reference to the super-entity. The diagrams below explain the two models.

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