Chapter4-DatabaseManagement

Chapter4-DatabaseManagement - DatabaseManagement Chapter4...

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Database Management Chapter 4 Copyright ©2010 Annette & George Easton 1
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2 Data Concepts Data   raw facts that are collected and  stored Information   data that has been  organized and/or processed to have  meaning or value To be useful, information must also be  Accurate Complete Economical Relevant Timely Verifiable 2
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3 Difficulties of Managing Data Volume of data is increasing exponentially. in 2006 amount of new information that was created was 3  million times the information in all books ever written  ~ 161 Exabytes  of new information in 2006  (1 Exabyte ~ 1.07 billion  gigabytes) by 2010 annual amount of new information estimated at 1000  Exabytes Data is created and collected by many  individuals using various methods and  devices. Data come from many sources including internal  sources, personal sources and external sources. Data security, quality and integrity are  critical. An ever-increasing amount of data needs to  be considered in making organizational 
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4 Hierarchy of Data Bit  (a binary digit): a switch that is either on or off. Byte:  group of 8 bits, represents a single character. Field:  name, number, or characters that describe an  aspect of a business object or activity.  Record:  collection of related data fields. File (or table):  collection of related records. Database:  a collection of integrated and related files.
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5 Electronic Data Representation Analog vs. digital signals Digital computers make use of the Binary  number system to represent data Each Binary Digit (BIT) has two states  On or Off Combinations of ones and zeroes represent  characters 8 bits = 1 byte  1 byte ~ 1 character 2 8  = 256 combinations of letters and numbers
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What are the Binary Equivalents  of the following Decimal  Numbers? Decimal Binary 5 1000s 100s 10s 1s 32s 16s 8s 4s 2s 1s 0 1 2 4 0 0 0 1 1 1 0 0 0 0 You can use an Excel function =DEC2BIN() to
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7 Data Representation Principle Coding Schemes   Sending a  character from the keyboard to the  computer Universal formats, not proprietary! i.e., not controlled by Microsoft or IBM  1.ASCII  2.EBCDIC 3.Unicode Sufficient for English and  Western European languages Unicode often  used for others ASCII “Text” format
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8 Data Hierarchy – traditional  database Database Student File Course File Faculty File Record1 Record2 Record3 Recordn Field1 Field1 Field1 Field1 Field1 Field1 Old SDSU database Separate Data Files Student records RedID, Lastname, firstname
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9 Two general techniques for managing  data File Management System approach The “traditional” approach characterized by multiple applications each 
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