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Jan 31, 2013 (4 years and 4 months ago)





The University of New Mexico

MGT 329/637

Database Management Systems

Last Revised:
3/18/2013 1:30 AM

Formal Definitions

Database (DB)

Integrated collection of data and


Data that describes other data

Database Management System (DBMS)

Application or system software that stores and
provides access to data stored in one or more

Data Integration

Modern organizations store and use petabytes (10

bytes) of data.

Data relates to all aspects of the organization

and financial, customers, suppliers, inventory, products,
production processes, competitors, R&D, …

Data are related to other data in many ways

for example:

An order to Dell for a laptop is based on a product catalog,
generates production and parts orders, and schedules assembly
and testing

Shipment/delivery of the laptop decreases inventory and results in
cash inflow or receivable that’s recorded in the customer account
and the financial statements

Changing an order before it enters production affects production,
inventory, ordering, future cash flow, and possibly incentives to
employees based on sales or profits

Data Integration


An efficient and effective information system
automatically recognizes and uses the
“connections” among data

for example:

To UNM, Stephen Burd is an employee, instructor,
faculty member, vendor, and student

Despite his multiple roles, descriptive data (e.g., name
and address) about him should be stored only once

Certain database updates are allowed for Burd that
might not be allowed for other persons

For example, it should be impossible for a student who isn’t
also an instructor to assign a grade in a course

Database Definition Revisited

Database (DB)

Integrated collection of data and

Integration implies that
relationships among data items

such as names, addresses, course titles, and grades
are recognized and stored within the system

For example:

A particular paycheck was deposited to Burd’s bank account

Burd enrolls in a particular course during a particular semester
and receives a grade for that course

The course Burd completed satisfies one requirement of a
particular degree program

Burd teaches a particular course and assigns grades to all
students enrolled in that course

Metadata Definition Revisited


Data that describes other data

Some types of metadata:

Single and multiple data item value constraints

for example:

Salary must be a positive number

Allowable grades are A, B, C, …

If grade is A then points earned is 4.0

If student status is “suspended” then currently enrolled credits must be zero

Data naming and organization

for example, the data item Name is part
of the Person table and is indexed alphabetically to speed alphabetic

Computation of derived values

e.g., how is grade point average
computed from grades earned


What users can view, change, or delete grades and salaries?


Where is a particular group of data items stored (on what disk
and machine)? If they’re stored in multiple places, which holds the
“original” or “master” and which are the copies?

Review Exercise

Pick a type of business or organization and
consider the data that it stores and uses in
ordinary operations

List 3
physical things

about which it stores data

Describe 3

among those things that
an “integrated collection of data” should store or

Describe 3 instances of metadata that should be
represented within the database

DBMS Definition Revisited

Database Management System (DBMS)

Application or
system software that stores and provides access to data
stored in one or more databases

Must support storage of data items, relationships among data
items, and metadata

Must be capable of managing multiple database

for example,
one for production and another for accounting

Must be flexible enough to support many kinds of data and
databases (many different application areas).

Must provide access to the data, preferably via a variety of paths
such as:

Direct access for end users via interactive and/or Web
based tools

Access via report generation tools

Access from application programs written in multiple languages (e.g.,
Java, Visual Basic, and Web scripts) executing locally and remotely

Must enable concurrent access by many users and applications

Key Database and DBMS Benefits

Data are more easily shared across application
programmers, users, and parts of an organization

Data are managed as an organizational resource


Security and privacy

Data as an asset

Application software is independent of many aspects of
data storage, especially physical ones

Data quality can be enforced consistently across
applications throughout the organization

Many changes to the database have no effect on existing

Data can be accessed without writing programs

Review Exercise

What’s the catch? (What do all of the benefits on
the previous page “cost”?)

Trains of thought

Friedman’s free lunch rule

there is no free lunch

Fisher on genetics and adaptation

highly specialized
organisms are efficient in their environment but can’t
easily adapt to other environments

The golden rule

s/he who has the gold makes the




before 1965:

Data are stored in computerized files.

Files contain records and records contain fields (numbers,
characters, and strings)

Computerized files are created for specific application
programs and groups of application programs (for
example, student grades, payroll, accounts payable)

Connections among files across application areas are
weak or nonexistent (for example, Burd has separate
student, employee, and vendor ID numbers with different
values and formats)

Redundancy among files is high (for example, Burd’s
address is stored in three different files which must all be
updated if he moves).

Database/DBMS History

First Era

First era


CODASYL Committee defines a standard
commonly called “network database”

Common data type definitions

Pointers among records represent relationships

Common access methods

Several mainframe products are matched to the

IMS and IDMS become the dominant

Rapid computerization of business processes fuels
demand for DBMSs

Most business applications
use them by the early 1980s

Database/DBMS History

Second Era

Second era


Relational database standard is developed in the
early 1970s.

Commercial relational DBMS products appear in
late 1970s, many based on experimental software
developed on UNIX running on minicomputers

Relational DBMSs gradually supplant CODASYL
DBMSs throughout the 1980s

Database explosion continues

fueled by
increasing automation levels, ever cheaper
computers and disk storage, and ever more data
intensive business practices

Database/DBMS History

Third Era

Third Era


Databases are ubiquitous

PCs, mainframes, supercomputers, business, science,
government, …

Large organizations have hundreds to tens of thousands of

integration across DBs is the big problem

Terabyte and petabyte databases become commonplace

Data is accessed globally from inside and outside the
organization (supply chain integration, direct customer
interaction, …)

ubiquitous networks, the Web, and
related standards make this possible

Relational DBMSs change little while software evolves
from structured to object
oriented tools and languages and
from machine
centered applications to distributed and
based applications

Standing at the Precipice

Organizations are overwhelmed by the volume of data

Data has value independent of its support for “ordinary” business
processing (e.g., marketing analysis for trends and new products)

Modern software views data and software as an integrated whole (the
oriented view) but relational DBMSs treat them separately

Relational DBMSs are a poor fit to modern software and applications

limiting the kinds of data that can be stored and the types of applications
that can be feasibly built and maintained (e.g., genome analysis and
customized drug design and production using a relational

The sheer volume of data stored in relational databases and the
dependence of “everything” on those databases and their host DBMSs
makes fundamnetal change almost unthinkable.

What is a DBMS?

DBMSs can be small
scale (e.g., Microsoft
Access) or large
scale (e.g., Oracle).

For medium

and large
scale applications, a
DBMS is a large, complex, and expensive program

Characteristics of that program include:

Tightly bound to the operating system since both share
responsibility for accessing disk storage, network I/O,
and control of related hardware resources.


industrial strength DBMSs require
strength hardware costing thousands to tens
of millions of dollars.

Difficult to manage

requires an army of highly

Some DBMS Products


Access (Jet)






Open Source: mySQL, PostgreSQL, Firebird


SQL Server Mobile

Open Source

Who Creates/Manages Your Database?

End User

Only feasible for small databases using simple DBMSs
(e.g., a customer list with order detail on Microsoft


Gathers user requirements

Designs applications

Implements information systems

Database Administrator (DBA)

Database design/development

Plans, creates & maintains database