The Data Model Resource Book, Volume 3: Universal Patterns for Data Modeling

Silverston c01.tex V2 - 11/21/2008 2:57am Page 23

Conventions and Standards Used in This Book 23

highlighted, they are identified by boldface lowercase letters. For example,

manufactured by could be the way a relationship may appear in the text of

this book.

Table 1-2 Data Types Used in the Book

DATA TYPE TYPE OF VALUES THAT THIS

WOULD INCLUDE

ID A non-meaningful identifier used to specify primary keys.

This would normally be a (positive) sequence number that

increments. For example, 1, 2, 3, 4, 5, and so on.

DATE The day, month, and year, for example, Sep. 5, 9/5/2003.

We don’t specify any particular format for dates. However,

in the table examples in each chapter we express dates in

the form, Mon. DD, YYYY. For example, Feb. 15, 2006.

DATETIME The date and the time of day that would be provided by a

clock, for example, 3/4/10 4:13 p.m. We don’t specify any

particular format for datetimes such as 12 or 24 hour

specifications.

CHAR Characters, or in other words, a text string.

DESC A description that expresses information about the nature

of the entity and is generally a larger text string than a CHAR

data type.

IND An indicator or flag. This means that there may be only two

possible values for the attribute. For example, ‘‘Y(es)’’ or

‘‘N(o)’’ or ‘‘M(ale)’’ or ‘‘F(emale)’’.

NUMBER A positive or negative numeric value, including

floating-point values as well, for example, 125, 1.0, 9.25,

-45 and so on.

MONEY