Transcript Photoshop: Creative Uses

Database Comparisons:
An Overview
Instructor: Vicki Weidler
Assistant:
Overview
• Understand what to look for when choosing a database
solution
• Define basic database terminology
• Describe different database models
 Flat file
 Nested
 Hierarchical
 Object-Oriented
 Network
 Hybrid
 Relational
• Explain the advantages and disadvantages of each
model
• Compare MS Excel, MS Access, FileMaker Pro & MS
Visual FoxPro
What is a Database?
• Collection of data
• Stored for a specific purpose
• Easily accessed, managed, &
updated
• Electronic filing system
What is a DBMS?
• Database Mgmt System
• Extra layer of software between
the applications programs and the
physical access to the data
Database Models
• “Description” of
– Container for data
– Methodology for storing and retrieving data
• Abstractions (i.e. mathematical
algorithms & concepts)
• Advancements have increased
database efficiency
Timeline
Late 1950’s
• File-oriented
• Flat file model
Early 1960’s
• Paper tape
storage used
briefly
• Limited govt &
commercial use
• Magnetic tape
replaced it
• Punch cards
• Mechanical
movement using
tapes & tape
drives
• Large mainframes
• Sequential file
access
1960’s
• Large corporations
developed their own
transaction
processing systems
• Mainframe disk
pack storage
medium of choice
• Assembler,
COBOL, Fortran,
PL/1
• Flat file storage &
retrieval
techniques
Timeline
1960’s
• Submit work orders
to programmers to
write a program to
display the info they
needed
• Caused backlogs &
long delays before
they could see/use
info
Flat File Model
Name
Address
Course
Grade
Eric Tachibana
123 Kensington
Chemistry 102
C+
Eric Tachibana
123 Kensington
Chinese 3
A
Eric Tachibana
123 Kensington
Human
Cultures
B
Eric Tachibana
123 Kensington
English 101
A
Tonya Lippert
88 West 1st St.
Psychology 101
A
Tonya Ducovny
100 Capitol Ln
Psychology 102
B-
Tonya Lippert
88 West 1st St.
European Govt
A
Data Hierarchy & Data Storage
BITS (0,1/binary digit)
BYTES (8 bits/ASCII/EBCDIC)
FIELDS (group of related bytes)
RECORDS (group of related fields)
FILES (group of related records)
DATABASES (group of related files)
Timeline
1964-1965
• Hierarchical data
model concept
1966
• IBM released first
1970’s
• Proliferation of
commercially
available DBMS
hierarchical model
products
• Called IMS (Info
Mgmt System)
• Private within each
organization; no
public access to the
database
• Based on
hierarchical model
• Random/direct file
access
Hierarchical Model Continued
Root
(Parent)
Level 1 Child
Level 2 Child
Level 1 Child
Level 1 Child
Level 2 Child
Level 2 Child
Hierarchical Model Continued
Hierarchical Model Continued
Hierarchical Model Continued
Timeline
1957
• U.S. Dept. of
Defense founded
CODASYL to
develop computer
programming
languages
1964-1965
• Network data model
developed
1967
• GE developed IDS
based on network
model
• Honeywell produced
IDS-2
Timeline
1969
• CODASYL Database
Task Group set
standards for
network database
products
1970’s
• Proliferation of
network model
products
• Major player was
Cullinet software
which developed
IDMS using the
network model
• IDMS commands
were embedded in
programming
languages & used
on mainframe
systems
• Mid-range
computers called
minicomputers were
developed
Market
Research
Name,
Address,
Telephone #
Management
Group
Social Security
Info
Human
Resources
Job Function
Timeline
1970’s
• Dr. E.F. Codd, IBM
researcher,
proposed relational
data model theory
• IBM developed a
relational model
prototype called
System R
1980’s
• IBM released first
commercial
relational database
called SQL/DS
(Structured Query
Language/Data
System) for its
mainframes
• IBM brought PCs to
the market
• IBM produced DB2
(SQL-based) for mainframes with batch
operating system
1980’s
• Microrim created
RBASE
• ANSI adopted SQL
as a standard
• Borland produced
Paradox
• Late 1980’s, objectoriented model was
born
Timeline
1990’s
• Microsoft bought
Fox Pro Software
• Microsoft released
MS Access
• SAP R/3 released
for client/server
environment
• Power of LANs
became evident &
migration to client/
server systems
1990’s
• Telecommunications
infrastructure
created for the
Internet & first public
access to WANS
(worldwide network of
networks)
• Microcomputers
became more common
in the workplace
• Desktop computers
had equivalent power
to mainframe systems
of the 1960’s
1990’s
• Using LANs, the
corporate database
might still reside on
the mainframe, but
data also could be
downloaded &
analyzed on the
desktop
• Past models
primarily stored text
& numeric data
Relational Terminology
Table/Relation/ Field/Attribute
Entity Set
(Column)
(File)
Record/Tuple
(Row)
Record/Tuple
(Row)
Record/Tuple
(Row)
Field/Attribute
(Column)
Relational Model Continued
Timeline
1990’s
• Desktop computing
included GUI
(graphical user
interfaces) &
multimedia
capabilities
• DBMS had to adapt
new capabilities
• Databases now
include text data,
but also objects
Object-Oriented Database Model
• Some objects may have multimedia characteristics
(i.e. drawings, sound bites or video clips)
• Example: CAD engineering drawing might include
operations to rotate or enlarge
• Object-oriented database systems (OODBMS) have been
developed as a result of object oriented programming
techniques
• In an object-oriented database, data encapsulated with
the valid operations on that data
• Some applications may require an OODBMS
• However, b/c of the time and cost involved, many
organizations are hesitant to convert their existing
transaction systems to object-oriented methodologies
Object-Oriented Programming
• Object-oriented programming designed
specifically for the purpose of creating objects
composed of reusable software code
• Using OOP, programmers can build programs
using chunks or modules consisting of
preassembled code and data
• Conventional programming is like building a
car a piece at a time, screw-by-screw
• OOP is more like building a car in modular
fashion
Hybrid Models
• Nested
• Object-Relational
Advantages of Nested Model
•
•
•
•
•
•
Fast & flexible development
No problems handling complex textoriented data structures
Low administrative costs
Usually simpler to administer than
RDBMS
More efficient
More users on less power & memory
Disadvantages of Nested Model
•
•
•
•
•
•
Minor market segment when compared to RDBMS
market
In early days, PICK was prone to data corruption
Today, reliability just as good as relational DBMS
Has transaction logging & similar features built in
Data query language, although easier to use than
SQL, was “not SQL” and associated tools for data
querying could not be used against a nested DBMS
Now most can be queried using SQL
Timeline
Late 1990’s
• Object-relational
approach
• Illustra (commercial
version of Univ of
California-Berkeley’s
POSTGRES project)
which was
subsequently
bought by Informix
Late 1990’s
• Debate ensued as to
whether hybrid
object-relational
DBMS like Oracle8
or Informix/Illustra
will prove more
effective at handling
future requirements
than a pure
OODBMS
Current Status
• Because of the need to store large multimedia files, the
object-oriented approach to databases seems to be
gaining in popularity, but many organizations continue
to use relational databases b/c of the power and userfriendly interfaces these systems provide. Both play a
role today.
• DBMS allow for several users to access data in a
database from different perspectives, and also allow for
users to have varying access rights in terms of
entering, manipulating, and retrieving data. By
empowering the end users, organizations can run at a
very efficient pace.
Evolution of data storage & retrieval
techniques & emergence of DBMS
• Increasingly powerful hardware has made it possible to
handle ever-increasing volumes of data
• Data warehousing & consumer profiling have major
commercial value
• Evolution of telecommunications & computer networks
has made data sharing & data collection more prevalent
• Security and privacy have become major concerns
• Volumes of data that are being collected and
availability of data on the Internet
• Programming languages like HTML, Java, & Perl are
used to develop Web applications
Evolution of data storage & retrieval
techniques & emergence of DBMS
• Firewalls have been developed to protect hardware,
software, and databases from unauthorized access or
destruction from hackers via the Internet
• Each new technology has had an impact on data
organization
• ColdFusion is an example of an application server that
interprets special commands embedded in HTML to
interact with a database; gaining popularity among web
developers for its ability to manage a website through a
database & its ease of coding
• Developers beginning to embrace XML to create
database-driven websites where the content for each
web page is stored in a database
Why use a DBMS?
• DBMS provides an interface to access data from
a variety of different views
• Help control data redundancy & data integrity
with several tools that help the user manage the
data
• Commercial DBMS’s have tools to define data
structure, security for protecting data, query
features, reporting features, utilities for
administering, tracking and monitoring data
access
Why use a DBMS?
• DBMS include a data dictionary which contains
descriptions of individual data items
• This allows record descriptions to be removed from the
programs so that when new fields are added, changed, or
deleted, only the data dictionary needs to be changed &
the application programs might not have to be changed
• Also, access methods are determined by database
software and do not have to be coded in the applications
programs
• Major feature of DBMS is the automatic collection &
storage of the metadata (data about the data)
• Metadata are kept in the data dictionary which includes
the correct spelling of each field name, data type for the
field, length of the field, descriptions of valid content for
the field
Why use a DBMS?
• Data dictionary is stored as part of the database and is
automatically built by using the data definition language
(DDL) of the DBMS
• All DBMS contain data definition language (DDL) which
allows access to the meta-data or descriptions of the data
& data manipulation language (DML) which allows access
to the actual data
• Data dictionary is a table of tables containing a list of all
the tables as well as the structure of the tables & special
info about the database itself
Why use a DBMS?
• Data integrity refers to the accuracy or
correctness of the data
• Data validation rules (rules for determining the
accuracy of data) & corresponding error
messages can be entered as part of the DDL
and recorded in the data dictionary
• DBMS automatically checks input against the
rules in the dictionary and if necessary,
displays an error message for the user
• This greatly simplifies applications
programming
Why use a DBMS?
• Data Redundancy occurs when the same data are
stored in multiple locations
• Causes update problems
• Updates require that the data be changed in every
location
• Causes extra work and can cause data inconsistency if
it changes in some locations and not others
• In order to avoid this, relationships are established
between data files to reduce multiple instances of same
data
• Use relationships when there is a need to link data
items that are stored in one data file with records in
other files
Why use a DBMS?
• Another feature in DBMS is multiple user
access and user views
• Concurrent usage
• Automatic record locks that are applied to a
record when a user accesses that record to
make a change
• This prevents another user from accessing
that record a the same time
• Views can be customized and simple security
measures added to that view
Summary
• Understand what to look for when choosing a database
solution
• Define basic database terminology
• Describe different database models
 Flat file
 Nested
 Hierarchical
 Object-Oriented
 Network
 Hybrid
 Relational
• Explain the advantages and disadvantages of each
model
• Compare MS Excel, MS Access, FileMaker Pro & MS
Visual FoxPro
Conclusion
• Resources
• Questions & Answers
• Evaluations
• Thank You!!!