The associations between a person and its occupations are sored using table
person_groop. Groups' property apply ("When a person belongs to a group, it also belongs to all the ancestors of this group").
For example, a musician also belongs to the group of artists.
Field occus
In the database, occupations are also stored in a person's field,occus.
The rule applied for this field is: Field
occus contains only the most specific occupations.
This rule is implemented by
Person::addOccus().
Logic of field
occus is different from the logic of table person_groop.