DATA MODELING OVERVIEW - A Developer's Guide to Data Modeling for SQL Server - page 4

these features to provide a solution that best meets the needs of your
customer.
Our goal in this topic is to give you the know-how and skills you need
to design and implement data models. There is plenty of information out
there on database theory, so that is not our focus; instead, we want to look
at real-world scenarios and focus your modeling efforts on optimizing your
design for Microsoft SQL Server 2008. The concepts and topics we discuss
are applicable to older versions of Microsoft SQL Server, but some fea-
tures are available only in SQL Server 2008. Where we encounter this
problem we will point out the key differences or at least let you know that
the topic applies only to SQL Server 2008.
Before we go much further, there are a few terms you should be fa-
miliar with. Many of these terms you probably already know, but we want
to make sure that we are all on the same page.
Databases
What is a database? The simple answer is that a database is anything that
contains information. A database can be either logical or physical (or both).
You will hear many companies refer to any internal information as the
company's database. In fact, I once had a discussion with a manager of
mine as to whether a napkin could be a database. If you think about it, I
could indeed write something on a napkin and it could be a record.
Because it is storing data, you could call it a database. So why don't we
store all of our important information on napkins? The main reason is that
we don't want to lose a customer's order in the washing machine.
Seriously, when we store data we need a database that can hold infor-
mation in a logical way and allow data retrieval. When you think of a data-
base, you should really think of something with tables that are made up of
rows and columns. Each table contains information pertaining to a single
“topic,” and each row contains data about a single instance of that topic.
Figure 1.1 shows a simple logical model containing information about em-
ployees and their computers.