This chapter highlights the capabilities of MySQL Workbench as a
documentation tool using the sakila database as
an example. This is a sample database provided by MySQL and found in
the Example Databases section of the
http://dev.mysql.com/doc/ page. An EER diagram is an invaluable
aid to a quick understanding of any database. There is no need to
read through table definition statements; glancing at an EER diagram
can immediately indicate that various tables are related.
You can also see how tables are related; what the foreign keys are and what the nature of the relationship is.
Find below an EER digram showing all the tables in the
sakila database. This image was created using
the menu options ,
, .
The object notation style used in
Figure 16.82, “The sakila EER Diagram” is Workbench (PKs
only). This notation only shows primary keys and no
other columns so it is especially useful where space is at a
premium. The relationship notation is the default, Crow's Foot.
As the connection lines show, each table is related to at least
one other table in the database (with the exception of the
film_text table). Some tables have two foreign
keys that relate to the same table. For example the
film table has two foreign keys that relate to
the language table, namely
fk_film_language_original and
fk_film_language. Where there is more than one
relationship between two tables, the connection lines run
concurrently.
Identifying and nonidentifying relationships are indicated by
solid and broken lines respectively. For example, the foreign key
category_id is part of the primary key in the
film_category table so its relationship to the
category table is drawn with a solid line. On
the other hand, in the city table, the foreign
key, country_id, is not part of the primary key
so the connection uses a broken line.