Lecture 18 - ER diagrams

Lecture 18 - ER diagrams - Section this Friday Database...

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1 Database design: ER diagrams INFO/COM S 230: Intermediate Web Design and Programming Section this Friday • First part will be given to meeting with your final project team to talk about organization and finding a client. • Second part will be given to letting you work on Project 3 (and get help from your TA). • Attendance required (at least for the team meeting). Database design • Starting today: how to go from client requirements to a good relational DB schema • Today and next time: Entity- Relationship (ER) diagrams • After that: Normalization ER diagrams ER diagrams are a graphical means of displaying relationships between entity sets (hence the name); both entity sets and relationships can have attributes . Every DB text has a slightly different take on ER diagrams; we’ll use a form from a book by Garcia-Molina, Ullman, and Widom (in the coursepack). Entity sets An entity is an abstract object of some sort. Entity sets are a collection of similar entities. E.g. Movies, Stars We’ll draw these using rectangles. Easy PDF Creator is professional software to create PDF. If you wish to remove this line, buy it now.
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2 Relationship sets A relationship is an association among two or more entities. A collection of similar
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