Basisdata Databases Williams B K Stacy C Sawyer

Basisdata (Databases) Williams, B. K, Stacy C. Sawyer (2007). Using Information Technology: A Practical Introduction to Computers & Communications. Seventh Edition, Mc. Graw-Hill, New York. ISBN-13: 978 -0 -07 -110768 -6 1

Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : • menjelaskan: hierarkhi data, key-filed, tipe file, metode akses dan penyimpanan data; pengertian dan keuntungan sistem manajemen basisdata, dan jenis-jenis akses basisdata yg utama(C 2) 2

Outline Materi • • • Managing Files: Basic Concepts Database Management Systems Database Models Data Mining The Ethics of Using Databases 3

Managing Files: Basic Concepts • A database is a logically organized collection of related data designed and built for a specific purpose • Data is stored hierarchically for easier storage and retrieval • Files: collections of related records • Records: collections of related fields • • Field: unit of data containing 1 or more characters Character: a letter number or special character made of bits • Bit: a 0 or 1 8 -4

Managing Files: Basic Concepts • Key Field – the field that identifies a record – Often an identifying number, such as social security number – Primary keys must be unique • Keys are used to pick records out of a database • Unique keys make records stand out from each other • If two records had the same key, then you might not pick the correct one – Nonprimary keys are used to sort records in different ways – Foreign keys are fields that appear in two different tables and are used to relate one table to another 8 -5

Managing Files: Basic Concepts This example shows a sample database in Microsoft Access. Products is a table. Product. ID is the primary key of the Product table. Product. ID is also a foreign key in the Orders table 8 -6

Managing Files: Basic Concepts • Program files are files containing software instructions – Source program files are written by the software developer in the programming language • Double-clicking on them won’t run them • They have file extensions like. cpp, . jav, . bas – Executable files are program files translated so they can be executed on the computer • Double-clicking on them will cause them to run • They have file extensions like. exe or. com 8 -7

Managing Files: Basic Concepts • Data files are files that contain data such as words, numbers, pictures, or sounds – These are the files that are used in databases – They have extensions such as. txt. mdb, and. xls – Graphics files have extensions like. tiff, . jpeg, and. png – Audio files have extensions such as. mp 3, . wav, and. mid – Animation/video files have extensions such as. qt, . mpg, . avi, and. rm • Data files are often compressed to save space and transmit them faster – Compression removes repetitive elements from a file 8 -8

Database Management Systems • Software written specifically to control the structure of a database and access to the data – Reduced data redundancy • Redundant data is stored in multiple places, which causes problems keeping all the copies current – Improved data integrity • Means the data is accurate, consistent, and up to date – Increased security • Limits who can create, read, update, and delete the data – Ease of data maintenance • Offer validation checks, backup utilities, and procedures for data inserting, updating, and deletion 8 -9

Database Management Systems 3 Principal Components • Data Dictionary – A repository that stores the data definitions and descriptions of the structure of the data and the database • DBMS Utilities – Programs that allow you to maintain the database by creating, editing, deleting data, records, and files – Also include automated backup and recovery • Report Generator – Program for producing an on-screen or printed document form all or part of a database 8 -10

Database Management Systems Database Administrator • Database Administrator (DBA) – A high-paid, responsible position within an organization – Coordinates all related activities and needs for an organization’s database – Ensures the database’s • • • Discussion Question: Did you know that 93% of companies that lost their data center for 10 days or more due to a disaster filed for bankruptcy within a year? Recoverability Integrity Security Availability Reliability Performance 8 -11

Database Management Systems Database Administrator • • • U. S. businesses lose over $12 billion per year because of data loss. Hardware or system failure accounts for 78% of all data loss. Human error accounts for 11% of all data loss. Software corruption account for 7% of all data loss. Natural disasters account for only 1% of all data loss. More vital data is being stored in smaller spaces. Instant access to electronic data has become more crucial in day-to-day business. Disaster prevention and recovery plans are often overlooked or outdated. Backup tools and techniques are not 100% reliable. 93% of companies that lost their data center for 10 days or more due to a disaster filed for bankruptcy within one year of the disaster. 12

Database Models • Hierarchical Databases – Fields or records are arranged in related groups resembling a family tree with child (low-level) records subordinate to parent (high-level) records – Root record is the parent record at the top of the database, and data is accessed through the hierarchy – Oldest and simplest; used in mainframes 8 -13

Database Models • Network Database – Similar to a hierarchical database, but each child record can have more than one parent record – Used principally with mainframe computers – Requires the database structure to be defined in advance 8 -14

Database Models • Relational Database – Relates or connects data in different files through the use of a key, or common data element – Examples are Oracle, Informix, Sybase – Data exists independently of how it is physically stored – Users don’t need to know data structure to use the database – Uses SQL (structured query language) to create, modify, maintain, and query the data – Query by Example uses sample records or forms to allow users to define the qualifications for choosing records 8 -15

Database Models • Object-oriented Databases – Use “objects”, software written in small, manageable chunks, as elements within data files – An object consists of • Data in any form, including audio, graphics, and video • Instructions on the action to be taken with the data – Examples include Fast. Objects, Gem. Stone, Objectivity DB, Jasmine Object Database, and KE Express – Types include • Web database • Hypermedia database 8 -16

Database Models • Multidimensional Database – Models data as facts, dimensions, or numerical answers for use in the interactive analysis of large amounts of data for decisionmaking purposes – Allows users to ask questions in colloquial English – Use OLAP (Online Analytical Processing) software to provide answers to complex database queries 8 -17

Data Mining • Is the computer-assisted process of sifting through and analyzing vast amounts of data to extract hidden patterns and meaning and to discover new knowledge • Data is fed into a Data Warehouse through the following steps – – Identify and connect to data sources Perform data fusion and data cleansing Obtain both data and meta-data (data about the data) Transport data and meta-data to the Data Warehouse • Data Warehouse is a special database that shows detailed and summary data from multiple sources 8 -18

Data Mining • Methods for searching for patterns in the data and interpreting the results – Regression analysis • Develops a formula to fit patterns in the data that has been extracted • Formula is applied to other data sets to predict future trends – Classification analysis • A statistical pattern recognition process that is applied to data sets with more than just numerical data 8 -19

Data Mining • Applications include – A phone company identifying customers with large bills, who were really small businesses trying to pay the cheaper residential rate – A coach in the Gymnastics Federation used it to discover what long-term factors contributed to athletes’ performance – Retail stores use it to predict future purchase patterns to help them choose which products to stock for the future 8 -20

The Ethics of Using Databases • Identity Theft concerns – A crime in which thieves hijack your identity and use your good credit rating to get cash, take out loans, order credit cards, and buy things in your name • Privacy concerns – Name migration: getting endless junk mail and telemarketing calls – Résumé rustling and online snooping – Government prying and spying Discussion Question: Has any one had their identity stolen? How long did it take you to get it straightened out? 8 -21

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