Modern Database Chapter 1 – Flashcards
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Database
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An organized collection of logically related data
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Data
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Stored representations of objects and events that have meaning and importance in the user's environment.
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important structured data types
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numeric, character, and dates
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Information
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data that have been processed in such a way as to increase the knowledge of the person who uses it
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Metadata
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data that describe the properties or characteristics of end-user data and the context of those data. metadata show data item name, data type, length, minimum and maximum values
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data storage
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data can be stored in files or databases
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before databases
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companies relied on file processing systems
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disadvantages of file processing
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1. program-data dependence 2. duplication of data 3. limited data sharing 4. lengthy data sharing 5. lengthy development times 6. excessive program maintenance
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data model
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graphical systems used to capture the nature and relationships among data
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entity
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a person, a place, an object, an event, or a concept in the user environment about which the organization wishes to maintain
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attribute
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the data you capture about an entity e.g. Customer Name
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instance
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each customer's information is referred to as an instance
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relational database
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a database that represents data as a collection of tables in which all data relationships are represented by common values in related tables
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Database management system (DBMS)
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a software system that is used to create, maintain, and provide controlled access to user databases
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Advantages of Database Approach
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1. Program-data independence 2. Planned data redundancy 3. Improved data consistency 4. Improved data sharing 5. Increased productivity of application development 6. Enforcement of standards 7. Improved data quality 8. Improved data accessibility and responsiveness 9. Reduced program maintenance 10. Improved decision support
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data independence
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the separation of data descriptions from the application programs that use the data
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user view
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a logical description of some portion of the database that is required by a user to perform some task
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cost of data quality problems as estimated by TDWI
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$600 billion each year
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constraint
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a rule that cannot be violated by database users. Improving data quality
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Costs and Risks of Database Approach
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1. New, Specialized Personnel 2. Installation and Management Cost and Complexity 3 Conversion Costs 4. Need for Explicit Backup and Recovery 5. Organizational Conflict
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Computer-aided software engineering tools (CASE)
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tools automated and used to design databases and application programs
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Repository
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centralized knowledge base for all data definitions, data relationships, screen and report formats, and other system components
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DBMS
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software system that is used to create, maintain, and provide controlled access to user databases
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database
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organized collection of logically related data
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Application programs
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used to create, maintain databases and provide information to users
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enterprise resource planning (ERP)
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business management system that integrates all functions of the enterprise, such as manufacturing, sales, fiance, marketing. software apps that provide the data necessary for enterprise to examine and manage its activities.
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Data Warehouse
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an integrated decision support database whose content is derived from the various operational databases.
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Enterprise data modeling
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first step in database development, in which the scope and general contents of orgnizatonal databases are specialized.
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Systems Development Life Cycle (SDLC)
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complete set of steps, the traditional methodology used to develop, maintain, and replace information systems
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SDLC
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1. Planning-Enterprise Modeling 2. Planning-Conceptual Data Modeling 3. Analysis-Conceptual Data Modeling 4. Design-Logical Database Design 5. Design-Physical Database Design and Definition 6. Implementation-Database Implementation 7. Maintenance-Database Maintenance
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Prototyping
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an iterative process of systems development in which requirements are converted to a working system that is continually revised through close work between analysts and users.
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Agile Software Development
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approach to database software development that emphasizes individuals and interactions over processes and tools, working software over comprehensive documentation, customer collaboration over contract negotiation, and response to change over following a plan.
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The Three Schemas
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defined by ANSI 1. External schema 2. Conceptual schema 3. Internal schema
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project
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planned undertaking of related activities to reach an objective that has a beginning and an end.
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SDLC
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1. Planning 2. Analysis 3. design 4. implementation 5. maintenance
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conceptual schema
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provides a complete, technology free picture of the database
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internal schema
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specifies the complete database as it will be stored in computer secondary memory in terms of logical schema and a physical schema
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external schema
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or user view, which describes the database relevant to a specific set of users
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nine major components database environment
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1.CASE 2.Repository 3.DBMS 4.Database 5.Application programs 6.User interface 7.Data and database admins 8.Systems Developers 9.End Users
