Dealing with many-to-many relationships

In the previous chapter, Chapter 8, Data Modeling Components, we discussed different relationship cardinalities. We went through some scenarios to understand one-to-one, one-to-many, and many-to-many relationships. We showed examples of creating a many-to-many relationship between two tables using non-key columns.

While creating a many-to-many relationship may work for smaller and less complex data models, it can cause severe issues and ambiguities in more complex models. In some cases, we may get incorrect results in totals; we might find some missing values or get poor performance in large models; while in other cases, we may find the many-to-many cardinality very useful.

The message here is that, depending on the business case, we may or may not use many-to-many cardinality; it depends on what works best for our model to satisfy the business requirements.

For instance, the many-to-many cardinality works perfectly fine in our...