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Database Definition For Beginners

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Definitions Database: organized collection of logically related data Data: stored representations of meaningful objects and events Structured: numbers, text, dates Unstructured: images, video, documents Information: data processed to increase knowledge in the person using the data Metadata: data that describes the properties and context of user data Data in context Summarized data Disadvantages of File Processing Program-Data Dependence All programs maintain metadata for each file they use Duplication of Data Different systems/programs have separate copies of the same data Limited Data Sharing No centralized control of data Lengthy Development Times Programmers must design their own file formats Excessive Program Maintenance 80% of information systems budget Problems with Data Dependency 1) Each application programmer must maintain his/her own data 2) Each application program needs to include code for the metadata of each file 3) Each...
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learn for free Database Data Modeling Documenting rules and policies of an organization that govern data. BUSINESS RULES Statements that define or constrain some aspect of the business. Examples: 1) Every student in the university must have one or more faculty advisers. 2) Every student in the university is assigned to one discipline only. Is this a business rule? A student is any person who has applied for admission or taken a course or training program from any credit or noncredit unit of the university A GOOD BUSINESS RULE IS: Declarative – what is required from system 1)Precise – Non-Ambiguous 2)Atomic – one statement 3)Consistent – does not contradict other rules 4)Expressible – structured, natural language 5)Distinct – non-redundant 6)Business-oriented – understood by business people CONCEPTUAL MODELING Entity-Relationship Model 1) A logical representation of data for an organization 2) Expressed in terms of entities, attributes and relationships Ent...
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