1
2
Historical Development of Database Technology
1
-
Early
Database
Applications
:
The
Hierarchical
and
Network
Models
were
introduced
in
mid
1960
’s
and
dominated
during
the
seventies
.
A
bulk
of
the
worldwide
database
processing
still
occurs
using
these
models
.
2
-
Relational
Model
based
Systems
:
The
model
that
was
originally
introduced
in
1970
by
Edgar
Codd
,
was
heavily
researched
and
experimented
with
in
IBM
and
the
universities
.
3
-
Object
-
Oriented
Applications
:
OODBMS
were
introduced
in
late
1980
’s
and
early
1990
’s
to
cater
to
the
need
of
complex
data
processing
in
CAD
(Computer
Aid
Design)
and
other
applications
.
Their
use
has
not
taken
off
much
.
4
-
Data
on
the
Web
:
Web
contains
data
in
HTML
with
links
among
pages
.
This
has
given
rise
to
a
new
set
of
applications
and
E
-
commerce
is
using
new
standards
like
XML
(
eXtended
Markup
Language)
.
Basic
Definitions
Database
:
A
collection
of
related
data
.
Data
:
Known
facts
that
can
be
recorded
and
have
an
implicit
meaning
.
Mini
-
world
:
Some
part
of
the
real
world
about
which
data
is
stored
in
a
database
.
For
example,
student
grades
and
transcripts
at
a
university
.
Database
Management
System
(DBMS)
:
A
software
package/
system
to
facilitate
the
creation
and
maintenance
of
a
computerized
database
.
Database
System
:
The
DBMS
software
together
with
the
data
itself
.
Sometimes,
the
applications
are
also
included
.
3
4
A Database has the Following Implicit Properties:
1)
A
database
represents
some
aspect
of
the
real
world,
sometimes
called
the
mini
-
world
.
Changes
to
the
mini
-
world
are
reflected
in
the
database
.
2)
A
database
is
a
logically
coherent
collection
of
data
with
some
inherent
meaning
.
A
random
assortment
of
data
cannot
correctly
be
referred
to
as
a
database
.
3)
A
database
is
designed,
built,
and
populated
with
data
for
a
specific
purpose
.
It
has
an
intended
group
of
users
and
some
preconceived
applications
in
which
these
users
are
interested
.
5
Types of Database System
1
-
Traditional
Database
Applications
,
in
which
most
of
the
information
that
is
stored
and
accessed
is
either
textual
or
numeric
.
2
-
Multimedia
Databases
can
now
store
pictures,
video
clips,
and
sound
messages
.
3
-
Geographic
information
systems
(GIS)
can
store
and
analyze
maps,
weather
data,
and
satellite
images
.
4
-
Data
Warehouses
and
Online
Analytical
Processing
(OLAP)
Systems
are
used
in
many
companies
to
extract
and
analyze
useful
information
from
very
large
databases
for
Decision
Making
.
5
-
Real
-
time
and
Active
Database
technology
is
used
in
controlling
industrial
and
manufacturing
processes
.
6
-
Database
Search
Techniques
are
being
applied
to
the
World
Wide
Web
to
improve
the
search
for
information
that
is
needed
by
users
browsing
the
Internet
.
6
A Simplified Database System Environment
Stored Database
Definition
(Meta
-
Data)
Software to Process
Queries/Programs
Application Programs / Queries
Users/Programmers
DBMS
Software
Software to Access
Stored Data
Stored Database
Typical
DBMS
Functionality
1)
Define
a
Database
in
terms
of
data
types,
structures
and
constraints
.
2)
Construct
or
Load
the
Database
on
a
secondary
storage
medium
.
3)
Manipulating
the
database
querying,
generating
reports,
insertions,
deletions
and
modifications
to
its
content
.
4)
Concurrent
Processing
and
Sharing
by
a
set
of
users
and
programs
–
yet,
keeping
all
data
valid
and
consistent
.
5)
Protection
or
Security
measures
to
prevent
unauthorized
access
.
6)
Active
Processing
to
take
internal
actions
on
data
.
7)
Presentation
and
Visualization
of
data
.
7
8
Main Characteristics of the Database Approach
1
-
Self
-
describing nature of a database system:
A
DBMS
catalog
stores
the
description
of
the
database
:
The
description
is
called
meta
-
data)
.
This
allows
the
DBMS
software
to
work
with
different
databases
.
2
-
Insulation
between
programs
and
data
:
Called
program
-
data
independence
.
Allows
changing
data
storage
structures
and
operations
without
having
to
change
the
DBMS
access
programs
.
3
-
Data
Abstraction
:
A
data
model
is
used
to
hide
storage
details
and
present
the
users
with
a
conceptual
view
of
the
database
.
4
-
Support of multiple views of the data:
Each user may see a different view of the database, which describes
only the data of interest to that user.
9
5
-
Sharing
of
data
and
multi
-
user
transaction
processing
:
Allowing
a
set
of
concurrent
users
to
retrieve
and
to
update
the
database
.
Concurrency
control
within
the
DBMS
guarantees
that
each
transaction
is
correctly
executed
or
completely
aborted
.
OLTP
(Online
Transaction
Processing)
is
a
major
part
of
database
applications
.
Database Users
Users
may
be
divided
into
those
who
actually
use
and
control
the
content
(called
“Actors
on
the
Scene”)
and
those
who
enable
the
database
to
be
developed
and
the
DBMS
software
to
be
designed
and
implemented
(called
“Workers
Behind
the
Scene”)
.
Main Characteristics of the Database Approach [Continue..]
10
Database Users [Continue……]
1
–
Database
Administrators
:
Responsible
for
authorizing
access
to
the
database,
for
coordinating
and
monitoring
its
use,
acquiring
software,
and
hardware
resources,
controlling
its
use
and
monitoring
efficiency
of
operations
.
2
–
Database
Designers
:
Responsible
to
define
the
content,
the
structure,
the
constraints,
and
functions
or
transactions
against
the
database
.
They
must
communicate
with
the
end
-
users
and
understand
their
needs
.
3
–
End
-
users
:
They
use
the
data
for
queries,
reports
and
some
of
them
actually
update
the
database
content
.
4
-
Casual
:
Access
database
occasionally
when
needed
.
1
1
Database Users [Continue……]
5
-
Naïve
or
Parametric
:
They
make
up
a
large
section
of
the
end
-
user
population
.
They
use
previously
well
-
defined
functions
in
the
form
of
“canned
transactions”
against
the
database
.
Examples
are
bank
-
tellers
or
reservation
clerks
who
do
this
activity
for
an
entire
shift
of
operations
.
6
-
Sophisticated
:
these
include
business
analysts,
scientists,
engineers,
others
thoroughly
familiar
with
the
system
capabilities
.
Many
use
tools
in
the
form
of
software
packages
that
work
closely
with
the
stored
database
.
7
-
Stand
-
alone
:
Mostly
maintain
personal
databases
using
ready
-
to
-
use
packaged
applications
.
An
example
is
a
tax
program
user
that
creates
his
or
her
own
internal
database
.
12
Advantages of Using the Database Approach
1
-
Controlling
redundancy
in
data
storage
:
Redundancy
means
store
the
same
data
multiple
times
leads
to
problems
:
First
:
need
to
perform
a
single
logical
update
once
for
each
file
.
Second
:
storage
space
is
wasted
when
the
same
data
is
stored
.
Third
:
files
that
represent
the
same
data
may
become
inconsistent
.
2
-
Restricting
unauthorized
access
to
data
:
Users
or
user
groups
are
given
account
numbers
protected
by
passwords,
which
they
can
use
to
gain
access
to
the
database
.
A
DBMS
should
provide
a
security
and
authorization
subsystem
.
3
-
Providing
Storage
Structures
for
efficient
Query
Processing
:
Because
the
data
store
on
the
disk
.
Indexes
hash
data
structures,
suitably
modified
for
disk
search
.
Buffering
module
that
maintains
parts
of
the
database
in
main
memory
buffers
.
Optimization
module
of
the
DBMS
is
responsible
for
choosing
an
efficient
query
execution
plan
for
each
query
based
on
the
existing
storage
structures
.
13
Advantages of Using the Database Approach [Continue…]
4
-
Providing
Persistent
Storage
for
Program
Objects
:
Object
-
oriented
database
systems
are
compatible
with
programming
languages
such
as
C++
and
Java,
and
the
DBMS
software
automatically
performs
any
necessary
conversions
.
Hence,
a
complex
object
in
C++
can
be
stored
permanently
in
an
OODBMS
.
5
-
Providing
multiple
interfaces
to
different
classes
of
users
:
Because
many
types
of
users
with
varying
levels
of
technical
knowledge
use
a
database,
a
DBMS
should
provide
a
variety
of
user
interfaces
.
Both
forms
-
style
interfaces
and
menu
-
driven
interfaces
are
commonly
known
as
graphical
user
interfaces
(GUI
)
.
6
-
Representing
complex
relationships
among
data
:
A
DBMS
must
have
the
capability
to
represent
a
variety
of
complex
relationships
among
the
data
as
well
as
to
retrieve
and
update
related
data
easily
and
efficiently
.
14
Advantages of Using the Database Approach [Continue…]
7
-
Providing
backup
and
recovery
services
:
A
DBMS
must
provide
facilities
for
recovering
from
hardware
or
software
failures
.
8
-
Enforcing
integrity
constraints
on
the
database
:
DBMS
should
provide
capabilities
for
defining
and
enforcing
these
constraints
.
The
simplest
type
of
integrity
constraint
involves
specifying
a
data
type
for
each
data
item
.
These
constraints
are
derived
from
the
meaning
or
semantics
of
the
data
and
of
the
mini
-
world
it
represents
.
9
-
Permitting
Inferences
and
Actions
using
Rules
:
Some
database
systems
provide
capabilities
for
defining
Deduction
Rules
For
Inferencing
New
information
from
the
stored
database
facts
.
Such
systems
are
called
deductive
database
systems
.
Active
database
systems,
which
provide
active
rules
that
can
automatically
initiate
actions
when
certain
events
and
conditions
occur
.
15
Extending Database Capabilities for New Applications
1
-
Scientific
Applications
that
store
large
amounts
of
data
resulting
from
scientific
experiments
in
areas
such
as
high
-
energy
physics
or
the
mapping
of
the
human
genome
.
2
-
storage
and
Retrieval
of
Images
from
scanned
news,
Pc
photographs
or
medical
images
such
as
X
-
rays
or
MRI
(magnetic
resonance
imaging)
or
video
such
as
movies,
video
clips
or
PC
camera
video
.
3
-
Data
Mining
Applications
that
analyze
large
amounts
of
data
searching
for
the
occurrences
of
specific
patterns
or
relationships
.
4
-
Spatial
Applications
that
store
spatial
locations
of
data
such
as
weather
information
or
maps
used
in
(GIS)
.
5
-
Time
Series
Applications
for
example,
daily
sales
or
monthly
national
product
figures
.
16
WHEN NOT TO USE A DBMS
The
overhead
costs
of
using
a
DBMS
are
due
to
the
following
:
1
-
High
initial
investment
in
hardware,
software,
and
training
2
-
The
generality
that
a
DBMS
provides
for
defining
and
processing
data
3
-
Overhead
for
providing
security,
concurrency
control,
recovery,
and
integrity
functions
.
When a DBMS may be unnecessary
It
may
be
more
desirable
to
use
regular
files
under
the
following
circumstances
:
1
-
The
database
and
applications
are
simple,
well
defined,
and
not
expected
to
change
.
2
-
There
are
stringent
real
-
time
requirements
for
some
programs
that
may
not
be
met
because
of
DBMS
overhead
.
3
-
Multiple
-
user
access
to
data
is
not
required
.
17
MS Access Data
Types
Data
Type
Use
for
Size
Text
Text
or
combinations
of
text
and
numbers,
such
as
addresses
.
Also
numbers
that
do
not
require
calculations,
such
as
phone
numbers,
part
numbers,
or
postal
codes
.
Up
to
255
characters
.
Memo
Lengthy text and numbers, such as notes or
descriptions.
Up to 64,000 characters.
Number
Numeric data to be used for mathematical
calculations
1, 2, 4, or 8 bytes. 16 bytes for
Replication ID (GUID) only.
Date/Time
Dates and times.
8 bytes.
Currency
Currency values. Accurate to 15 digits to the
left of the decimal point and 4 digits to the
right.
8 bytes.
AutoNumber
Unique sequential (incrementing by 1)
4 bytes. 16 bytes for Replication ID
(GUID) only.
Yes/No
Fields that will contain only one of two values,
such as Yes/No, True/False, On/Off.
1 bit.
OLE Object
Objects (such as Microsoft Word documents,
Microsoft Excel spreadsheets, pictures, sounds,
or other binary data),
Up to 1 gigabyte (limited by disk space).
Hyperlink
Field that will store hyperlinks
Up to 64,000 characters.
Lookup
Wizard
Creates a field that allows you to choose a value
from another table or from a list of values using
a combo box
The same size as the primary key field
that is also the Lookup field; typically 4
bytes.
Enter the password to open this PDF file:
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