Database Reference
In-Depth Information
commonlyuseeXtensibleMarkupLanguage(XML)toassembleandconsolidatedatafrom
various relational and nonrelational systems. There has been a considerable effort by vari-
ous vendors to get their clients to create databases and store data in the “cloud,” that is, a
location that is completely apart from the client's location. The idea is that the client can
access data from the “cloud” database via the Internet from anywhere at any time. Given
the broad emergence and use of connected devices within the past few years (as of this
writing), it will be interesting to see how database management systems evolve within this
type of environment.
A Final Note
RDBMSsnowhavealonghistory,andtheycontinuetoplayahugeroleinthewaypeople,
businesses, and organizations interact with their data. Their role is constantly expanding
and evolving as data becomes more accessible via the Internet and businesses move at an
ever-increasing pace to expand their presence on the Web. Numerous organizations are
heavily invested in their relational database systems, and they are not likely to disappear
anytime soon.
Summary
We opened this chapter by defining the two types of databases currently used in database
management: operational databases and analytical databases.
Wethenbrieflydiscussedthehierarchicaldatabasemodelandthenetworkdatabasemodel.
Our discussion covered the data structures, relationships, and data access methods used
in both models, as well as their chief disadvantages. You learned that these models were
widelyusedintheearlydaysofdatabasemanagementandledtotheeventualdevelopment
and introduction of the relational database model.
Next,weprovidedadetaileddiscussionoftherelationaldatabasemodel,itshistory,andits
features. We noted that it is based on specific branches of mathematics and that this math-
ematical foundation is what makes the model so structurally sound. Then we explored the
model's data structures and relationships, and the role SQL plays in accessing data within
themodel.You'llremember,nodoubt,thatSQListhestandardlanguageusedtoworkwith
relational databases. We ended this section by reviewing the advantages of the relational
database model.
We then took a look at a brief history of relational database management systems, begin-
ning with the mainframe systems of the early 1970s and progressing through the PC-based
systems of the 1980s to the client/server systems of the 1990s. At this point you should
have a sense of the progression of circumstances that have led to the development of the
database systems we use today.
