= Update Detection during Imports =

Data imports can do both - create new records in the database and update existing ones.

If Sahana Eden can identify an import item with an existing record, this record will be updated rather than a new record being created.

In order to identify the import item, Eden uses a cascade of rules:

  1. Identification by UUID
  2. Identification by other unique keys
  3. Identification by table-specific rules

== Identification by UUID ==

Every record in the Sahana Eden database has a UUID field (universally unique identifier), see [wiki:UUID].

If an import item contains a UUID and it matches an existing database record, this record will be updated rather than creating a new record.
== Identification by Other Unique Keys ==

Some database tables use additional unique keys, e.g. the "name" field in organisations. These keys can be used instead of UUIDs to indicate updates - however: if there is also a UUID present in the import item, then only the UUID will be used to identify the record to update.

== Table-Specific Identification Rules ==

For many database tables, Sahana Eden has additional table-specific rules to identify records in cases where the import item does not contain a UUID and no match can be found by unique keys.

=== Person Records ===

   - ''tbw''