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

• Explain the advantages and disadvantages of each model• Compare MS Excel, MS Access, FileMaker Pro & MS Visual

FoxPro

Flat file Nested Hierarchical Object-Oriented Network Hybrid Relational

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 Early 1960’s

• File-oriented

• Flat file model

• Limited govt & commercial use

• Punch cards

• Large mainframes

• Paper tape storage used briefly

• Magnetic tape replaced it

• Mechanical movement using tapes & tape drives

• 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 1966

• Hierarchical data model concept

• IBM released first commercially available DBMS

• Called IMS (Info Mgmt System)

• Based on hierarchical model

1970’s

• Proliferation of hierarchical model products

• Private within each organization; no public access to the database

• Random/direct file access

Hierarchical Model Continued

Root (Parent)

Root (Parent)

Level 1 ChildLevel 1 ChildLevel 1 ChildLevel 1 Child Level 1 ChildLevel 1 Child

Level 2 ChildLevel 2 Child Level 2 ChildLevel 2 ChildLevel 2 ChildLevel 2 Child

Hierarchical Model Continued

Hierarchical Model Continued

Hierarchical Model Continued

Timeline

1957 1964-1965

• U.S. Dept. of Defense founded CODASYL to develop computer programming languages

• Network data model developed

1967

• GE developed IDS based on network model

• Honeywell produced IDS-2

Timeline

1969 1970’s

• CODASYL Database Task Group set standards for network database products

• 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

Management Group

Management Group

Job FunctionJob Function

Human Resources

Human Resources

Market Research

Market Research

Name, Address,

Telephone #

Name, Address,

Telephone #

Social Security Info

Social Security Info

Timeline

1970’s 1980’s

• Dr. E.F. Codd, IBM researcher, proposed relational data model theory

• IBM developed a relational model prototype called System R

• 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 main- frames with batch operating system

• Microrim created RBASE • ANSI adopted SQL as a standard

• Borland produced Paradox • Late 1980’s, object- oriented model was born

1980’s

Timeline

1990’s 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

• 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

• 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

1990’s

Relational Terminology

Table/Relation/Entity Set(File)

Field/Attribute(Column)

Field/Attribute(Column)

Record/Tuple(Row)

Record/Tuple(Row)

Record/Tuple(Row)

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 text-

oriented 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

• 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

Late 1990’s

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 user-friendly 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

• Explain the advantages and disadvantages of each model• Compare MS Excel, MS Access, FileMaker Pro & MS Visual

FoxPro

Flat file Nested Hierarchical Object-Oriented Network Hybrid Relational

•Resources•Questions & Answers•Evaluations•Thank You!!!

Conclusion