Lab%206%20-%20Data%20Attribute%20%26%20Data%20Entity%20Discovery

Lab%206%20-%20Data%20Attribute%20%26%20Data%20Entity%20Discovery

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DATA ENTITY DISCOVERY  LAB 6
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2 . DATA ENTITIES A data entity is a theoretical data object -  something about which you want to store  data. A data entity corresponds to a table in a  relational database. To help think about data entities,  consider a person.
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3 . DATA ATTRIBUTES People have various attributes that distinguish  them from other people. Height Weight Hair color Eye color Clothing Similarly, data entities have  data attributes – the data you want  to store about the entity. Data attributes correspond to fields in a relational database. Brown hat Blue coat
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4 . Northwind Shippers Data Entity. Three records, each with unique attributes for: ShipperID CompanyName -  SHOULD be named  ShipperName . Phone -  SHOULD be named  ShipperPhoneNumber .
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5 . WHY USE "ENTITIES" AND "ATTRIBUTES"  INSTEAD OF "TABLES" AND "FIELDS"? Tables and fields are relational database terms. Most information systems are implemented using  relational databases, but not all. Older, non-relational data systems (hierarchical databases  and object-oriented databases) still exist. XML is a growing non-relational web-enabled data format. Jumping too soon into implementation decision is not  a good idea. Limits how you think about the design. Ultimately limits your choices.  E ntities and Attributes  are implementation-neutral  terms.
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6 . DETERMINING ATTRIBUTES What are the data attributes on this form?  Start by examining the various entry boxes.  Forms will LIE to you. Why? Lack of physical space. The label on the form MAY NOT accurately describe that data.
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7 .
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This note was uploaded on 01/30/2012 for the course CNIT 180 taught by Professor Victorbarlow during the Spring '12 term at Purdue University-West Lafayette.

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Lab%206%20-%20Data%20Attribute%20%26%20Data%20Entity%20Discovery

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