N-ary associations

N-ary association pattern

The transformation of an n-ary association is mapped through the generation of an intermediary table stereotyped <<table>>, which contains the set of primary keys for the different classes positioned at the ends of the association.

The following example (Figure 44) shows the transformation of an association between three persistent classes.

Figure 44. Analysis model, modeling an n-ary association

After transformation, an intermediary table has been generated. This table is made up of the set of attributes modeled as primary key of the classes which take part in the n-ary association.

Figure 45. Physical model, modeling an n-ary association

*-* association pattern

An association of *-* multiplicity is treated as an n-ary association. For further information, please see the previous paragraphs.

Note: An association annotated {external} is managed like a *-* association.

A multiplicity not defined on the role of the association is dealt with as a * multiplicity.