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Understanding Data Files, Fields, and Keys in Databases: Concepts & Organization, Slides of Fundamentals of E-Commerce
An introduction to databases, discussing their purpose, organization, and key concepts such as data files, fields, records, and keys. It also covers the importance of unique key fields for searching records and the use of databases in various information systems. Additionally, it touches upon the differences between flat file databases and electronic databases.
Typology: Slides
2012/2013
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Databases
Lecture Objectives
• Database Concepts • Data Organization
in databases
• Key
Field
• Main activities in
Database Maintenance
– Defining data– Creating data– Manipulating data • Database
Usage
Data Organization in Databases Character
Character
Character Field
Record
Data File Cha.. Field
Cha.. Field……
Record :……….
A Database
Data File Data File ………..
Data Organization Example • In a University database
A^
L^
I
Field: Name
Record for Ali
File: Student 9 8 … Field: ID
(^7 0) Field: Score
Record for Rasheed Record for …
File: Course File: Faculty
UniversityDatabase
….Database Concepts
•^ Key Field^ – Searching a particular record uniquely in a data file
requires at least one field unique in value for all records – Example
, in STUDENT file StudentNumber is such a
field– Common
example of key values
(in daily life
databases)^ • Social Security Number• Driver’s License• Student ID Numbers
Electronic Databases
-^ Databases on some
electronic media like disks
-^ Computer programs are needed to
maintain/ use on disk
databases• Three main activities
for electronic database maintenance
-^ Defining^ •
Specifying the
data types
,^ data validation
rules etc. for the data values
-^ Creating^ •
Storing the data values (as defined by the user)
on some physical
medium
-^ Manipulating^ •
Querying/ searching/ updating the data values • Checking the conformance with the defined data constraints(validation rules)
Database
Implementation
Approaches
-^ Flat File Approach^ – Every data file is tried to be rich in all the relevant
details– Every data file is used on a localized basis (e.g. one filefor each department).– This makes every file independent of the other files inthe database – Benefit
: Data Reporting is easily done on each file
independently – Disadvantage
: Data inconsistencies may result due to
data redundancies (duplications)
A Flat File Database
A Student Grade Database^ •All the information needed is placed in one single data file•For example, a spreadsheet containing a single student grade file•No need to refer to any other file for data reporting Redundant data values
- In GRADE_REPORT:•Student’s personal information includes:^ StudentNumber, StudentName, Class, Major •Whenever a grade record for a student is inserted in the file, hispersonal information is repeated.
GRADE_REPORT
StudentID
Name
Class^
Major^
CourseCode
SectionCode
Grade
17 Smith
1 CS^
MATH
1 B
17 Smith
1 CS^
CS
1 C
8 Brown^
2 COE^
MATH
2 A
8 Brown^
2 COE^
CS
1 A
8 Brown^
2 COE^
CS
1 B
8 Brown^
2 COE^
CS
1 A