Lecture11 - Outline Lecture 11: Introduction to Relational...

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Lecture 11: Introduction to Relational Databases • Overview of relational databases Slides created by Dr. Curtis Dyreson 2 Outline What is a database? A traditional view Relational databases 3 Terminology Database – An organized collection of shared , persistent data. ! Organized – schema ! Persistent – disk storage ! Shared – support multiple readers/writers Database management system (DBMS) – The software to manage the collection. A DBMS evaluates a query to produce a set of results . 4 Traditional Data Management Example Scenario ! You are a video store owner. ! Customers rent video tape copies of movies. ! Several copies of each movie. Needs ! Which tapes has a customer rented? ! Are any tapes overdue? ! When will a tape become available?
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5 Solution: A File-based System Edit rented.txt file Customer : Jane Doe, Rented : Babe, Due : Jan. 19, 2000 Advantages ! Text editors are easy to use ! Simple to insert/delete/update records 6 Complication: Queries Does not address needs Query: What movies has Joe Jenkins rented? Execute (not quite right): Search for ‘Joe Jenkins’. Execute: Search for ‘^\s+ Customer :\s*Joe\s+Jenkins\s*,\s+ Rented :’. Query: Are any tapes overdue? Execute: ??? Requirements ! Robust, sophisticated query language ! Clear separation between data organization (schema) and data DBMS Concepts Schema DML SQL 7 Complication: Integrity Lacks data integrity , consistency ! Clerk misspells value/field Customer : Jane Doek , Rented : Eraserhead, Deu : Jan. 19, 2000 ! Inputs improper value, same value differently Customer : Jane Doe, Rented : The Eraserhead , Due : Feb. 29, 2000 ! Forgets/adds/reorders field Terms : weekly special Due : Jan. 19, 2000, Rented : Eraserhead Requirements ! Enforce constraints to permit only valid information to be input. DBMS Concepts Integrity constraints Types 8 Complication: Update Add/delete/update fields in every record ! Record store location.
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This note was uploaded on 01/20/2012 for the course MBIOS 478 taught by Professor Staff during the Fall '11 term at Washington State University .

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Lecture11 - Outline Lecture 11: Introduction to Relational...

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