The Relational System - Mastering phpMyAdmin 2.8 for Effective MySQL Management - page 155

The Relational System
Welcome to the part of the topic where we start to cover advanced features. The
relational system allows users to do more with phpMyAdmin, as we will see
in the following chapters. This chapter explains how to install the linked-tables
infrastructure, which is a prerequisite for the advanced features, and explains how to
define inter-table relations.
Relational MySQL?
When application developers use PHP and MySQL to build web interfaces or other
data manipulation applications, they usually establish relations between tables,
using the underlying SQL queries - for example, 'get an invoice and all its items' and
'get all topics by an author'.
In the first versions of phpMyAdmin, MySQL was storing information about which
table belonged to which database, but the relational data structure (how tables relate
to each other) was not stored into MySQL. Relations were temporarily made by the
applications to generate meaningful results. In other words, the relations were
in our head.
This was considered a shortcoming of MySQL by phpMyAdmin developers and
users, and so the team started to build an infrastructure to support relations. The
infrastructure evolved to support a growing array of special features. We can
describe this infrastructure as metadata (data about data).
phpMyAdmin 2.2.0 already had the bookmarks feature (being able to recall
frequently used queries, as described in Chapter 14), and version 2.3.0 generalized
the metadata system. Subsequent versions built on this facility, the latest addition
being the 2.5.x family with its MIME-based transformations (as described in
Chapter 16).