Sql Excel : Picturing the Structure of the Data

In the beginning, there is data. Although data may seem to be without form and
chaotic, there is an organization to it, an organization based on tables and
columns and relationships between and among them. Relational databases store
structured data—that is, tables with well-defined rows and columns.
This section describes databases by the data they contain. It introduces entityrelationship
diagrams, in the context of the datasets (and associated data models)
used with this book. These datasets are not intended to represent all the myriad
different ways that data might be stored in databases; instead, they are intended
as practice data for the ideas in the book. They are available on the companion
website, along with all the examples in the book.