ahlawat-ACC321_RelationshipExamples-3044171112

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Relationships between database tables: Cardinality & modality Dr. AHLAWAT 3/20/12
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Review D a t a b a s e e s s e An Entity Table -- a person, place or thing about which we want to collect and store multiple instances of data It has a name It has attributes (fields) that describe the data we are interested in storing. * employee-id employee-L- name employee-F- name EMPLOYEE 3/20/12 Dr.
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Relationships In the context of database, there are three basic types of relationships: 1) one-to-one, 2) one-to-many, and 3) many-to-many. 3/20/12 Dr.
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Relationship between two entities (tables) 3/20/12 Dr.
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Review D a t a b a s e e s s e Relationship -- illustrates the association between two entities (tables) It has a name. enroll 3/20/12 Dr. Student Course
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Relationships MINIMUM: expresses the minimum number of times one instance of an entity set must participate in a relationship 0 = optional participation 1 = mandatory participation MAXIMUM: expresses the maximum number of times one instance of an entity set may
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