M:N relations are a bit more complex. The most important fact is that the m:n relation must always be built on existing 1:n and n:1 relations. In fact, this type of relation links together two relations (not objects).

There are two types of n:m relations:

• A straightforward m:n relationship

  Example: M:N Relationship

• Time-related m:n relationship (which simulates a 1:n relationship at a given point in time).

  Example: Time Related M:N Relationship

When creating a new m:n relation type, the following sequence of wizard pages is available:

• Page 1: Enables you to select 2 object types which you want to work with.
• Page 2: Deals with the cardinality selection.
• Page 3: Deals with the relation mandatoriness.
• Page 4: Enables you to specify names of the relation attributes.
• Page 5: Generates the SQL script.
• Page 6: Prompts you to select a link table with foreign keys to the source and target object types.

• Page 7: The final step of the m:n relation creation.

Note: The number of pages which the wizard consist of largely depends on the type of relation being created. For instance, creating a transient relation requires less steps than creating an m:n relation.