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The CONCEPT_ANCESTOR table is designed to simplify observational analysis by providing the complete hierarchical relationships between Concepts. Only direct parent-child relationships between Concepts are stored in the CONCEPT_RELATIONSHIP table. To determine higher level ancestry connections, all individual direct relationships would have to be navigated at analysis time. The concept ancestor table includes records for all parent-child relationships, as well as grandparent-grandchild relationships and those of any other level of lineage. Using the CONCEPT_ANCESTOR table allows for querying for all descendants of a hierarchical concept. For example, drug ingredients and drug products are all descendants of a drug class ancestor.
This table is entirely derived from the CONCEPT, CONCEPT_RELATIONSHIP and RELATIONSHIP tables.
Field | Required | Type | Description |
---|---|---|---|
ancestor_concept_id | Yes | integer | A foreign key to the concept in the concept table for the higher-level concept that forms the ancestor in the relationship. |
descendant_concept_id | Yes | integer | A foreign key to the concept in the concept table for the lower-level concept that forms the descendant in the relationship. |
min_levels_of_separation | Yes | integer | The minimum separation in number of levels of hierarchy between ancestor and descendant concepts. This is an attribute that is used to simplify hierarchic analysis. |
max_levels_of_separation | Yes | integer | The maximum separation in number of levels of hierarchy between ancestor and descendant concepts. This is an attribute that is used to simplify hierarchic analysis. |