Database Design Using Entity-Relationship DiagramsEntity-relationship (E-R) diagrams are time-tested models for database development well-known for their usefulness in mapping out clear database designs. Also commonly known is how difficult it is to master them. With this comprehensive guide, database designers and developers can quickly learn all the ins and outs of E-R diagramming to become expe |
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assume atomic attended automobile Barker/Oracle-like model binary relationships building called candidate key cardinality Chapter Chen-like model City composite attributes concept connection consider courses create defined DEPARTMENT dependent depicted describe design methodology developed diagram discussed dorm draw drive employee enroll ER diagram example Exercise exist flight foreign key full participation grammar identify instructor intersection Jones Location look M:N relationship Mall mapping rules means middle multi-valued attribute normal notation Note null optional owner partial participation participation Pattern PERSON presented primary entity primary key PRODUCT record recursive relationship redundant References relational database requirements sample data shown in Figure side situation Smith specialization specification sport Step strong entity structural constraints STUDENT subdivided SUPPLIER Suppose Systems ternary relationship weak entity West Florida Mall
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Page 239 - Third Normal Form A relation that is in second normal form, and in which no nonkey attribute is functionally dependent on another nonkey attribute. Thus, there are no transitive dependencies. Three-Schema Architecture A...
Page 238 - Cardinality constraints specify the number of relationships that an entity can participate in (maximal participation) and furthermore whether the existence of an entity depends on its being related to another entity via the relationship type (minimal participation).
Page 237 - Key An attribute or data item that uniquely identifies a record instance or tuple in a relation.