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Pertemuan 17

Basisdata (Databases)

Matakuliah : T0604-Pengantar Teknologi Informasi

Tahun : 2008

Versi : 2.0/0.0

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

Sumber: Chapter 8. Databases & Information Systems: Digital engines for today’s economy, p.407

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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(C2)

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Outline Materi

• Managing Files: Basic Concepts

• Database Management Systems

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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

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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

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Managing Files: Basic Concepts

This example shows a sample database in Microsoft Access. Products is a table. ProductID is the primary key of the Product table. ProductID is also a foreign key in the Orders table

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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

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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 .mp3, .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

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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

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Database Management Systems3 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

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Database Management SystemsDatabase 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

• Recoverability• Integrity• Security• Availability• Reliability• Performance

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?

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Kesimpulan