Because current-generation DBMSs are easy to use, an unfortunate side effect is that many computer-savvy business
users gain a false sense of confidence in their ability to build a functional database. These users can effectively navigate
the creation of database objects, but without the proper understanding of database design, they tend to produce flawed,
overly simplified structures that prevent the system from correctly storing data that corresponds to business realities,
which produces incomplete or erroneous results when the data are retrieved. Consider the data shown in Figure 1.3,
which illustrates the storage of data about employees and skills. Some employees have not passed a certification test in
any skill, while others have been certified in several skills. Some certified skills are stored for several employees, while
other skills have no employees that hold those certifications.