relational database revised
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Database Operations Flat-File and Relational Database
Source: Chapter 7, Tomorrow’s Technology & You (8th ed) by G Beekman & M Quinn
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Objectives
So the students will be able to – Identify and discuss database
operations Understand and explain the various
special purpose databases Explain the difference between a flat-
file and relational database Explain the concept of one-to-one and
one-to-many relationships
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Database Operations
Imports data from other sources - from word processors, spreadsheets, or other databases
Browsing records Database queries Query – an information request; can
be a search for a specific record or all records that match a set of criteria
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Database Operations
Sorting Data – allows you to arrange record in alphabetic or numeric order based on values in one or more fields
Print reports, labels, and form letters
Display reports on screen or on printouts
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Database Operations
Complex queries – can be done using SQL (Structured Query Language)SQL , a special query language
featured in most database programUsed to filter the records of a
database, capturing only those that meet the specific criteria
Use common English language and common logical operator OR and AND.
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Database Operations
Use handout on – The Language of Database Queries
Example of SQL statements: Select Vehicle_ID, Vehicle_Type
FROM Rental_Vehicles WHERE Transport_Mode = ‘Land’ AND Rental_Price < 20.00
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Special-Purpose Database Programs (SPDPs)
Preprogrammed for specific data storage & retrieval purposes
Users do not need to define file structures or design forms because these were taken care of by the software
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Example of SPDPs
1. Directories – electronic phone
directory that pack millions of names & phone numbers onto a single CD-ROM or Web site
Electronic street atlas – uses information to provide location feedback for travelers & mobile workers from GPS feeds
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Example of SPDPs
2. Geographic Information Systems (GIS) – simple mapping and tracking programs that combines tables of data from various sources Displays geographic and
demographic data on maps
Enable users to see data relationships that might be invisible in table form
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Example of SPDPs
3.Personal Information Managers – can automate address / phone books, appointment calendars, to-do list, miscellaneous notes
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Types of database programs
1. File managers – a program that enables users to work with one file at a time.
Example: FileMaker Pro
2. Database Management System (DBMS) - a program that manipulate data in a large collection of files (database), cross-referencing between file as necessary
Example: MS Access, Oracle
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Type of Database structures
Flat-file database – a database in which all records are stored in one large table. For example, in a flat-file customer order, a customer’s address, phone number, & other important information will be entered over and over again every time a customer placed an order.
Characteristics of flat-file databases: It requires redundant data, which resulted
into files of large sizes. It is difficult to maintain because it
requires a large pool of human resources that equates to more salaries, office space and equipment.
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Example: Flat-file database
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Type of Database structures
Relational Database – a type of database which consists of more than one file or table that are linked to each other by a common data and in which changes in one file are reflected automatically in other related files.
The Relational Database Theory - solved the problem of redundant data (in a flat-file format).
Dr. E.F. Codd – introduced the relational database theory in his published paper entitled “A Relational Model of Data for Large Shared Data Banks” in 1970.
He introduced a set of rules that eliminate the need to store redundant data and formed the origin of relational database theory.
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Example of a
Relational
database
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Advantages of Relational databases
1. Eliminate redundant data reduces the number of times a data item is
entered therefore, minimizing data entry error. Each data item is stored only once, so if an error
is made, only one entry will be corrected.
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Advantages of Relational databases
2. Reduce data inconsistencies Data consistency – means rules or procedures
followed in the entry and processing are one and the same for all users
3. Protect data integrity Data integrity – concerned with the correctness
of data; data free from errors