Database Reference
In-Depth Information
There is also a line from
Author
to
Author
, which captures any relationship between au-
thors such as one author who wrote a topic review for another author or two authors who
are on the same tennis team, etc. A constraint that starts and ends on the same table, such
as this author constraint, is called a recursive relationship. (Recursive relationships will be
discussed in the next chapter.)
Let's contrast this traditional way of structuring data with the four varieties of NoSQL data-
bases. Here is how the author and title information can be captured in each of these four
types of databases:
