Relational database revised


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Relational database revised

  1. 1. Database Operations Flat-File and Relational Database Source: Chapter 7, Tomorrow’s Technology & You (8th ed) by G Beekman & M Quinn
  2. 2. 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
  3. 3. 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
  4. 4. 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
  5. 5. Database Operations  Complex queries – can be done using SQL (Structured Query Language) SQL , a special query language featured in most database program Used 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.
  6. 6. 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
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. Example of SPDPs 3.Personal Information Managers – can automate address / phone books, appointment calendars, to-do list, miscellaneous notes
  11. 11. 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
  12. 12. 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.
  13. 13. Example: Flat-file database
  14. 14. 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.
  15. 15. Example of a Relational database
  16. 16. 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.
  17. 17. 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