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er-model (1) - Entity-Relationship Model Leo Mark(May 2002...

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Entity-Relationship Model Leo Mark (May 2002)
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The Real World The Model real customers customer surrogates
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Entity Type and entity surrogates airport entity type names must be unique
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Single-valued Properties Hartsfield Kastrup Logan airport airport name property values are lexical, visible, audible, ….they are things that name other things
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Identifying Properties airport airport code for each identifying property value there is at most one instance of the identified entity every entity must be uniquely referenceable atl cph bos lax
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su th Multi-valued Properties flt-schedule weekdays we mo mo th we mo
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Composite Properties airport airport address airport street airport zip airport city 1 Flughafen St 400 Flight Av 12 Logan Rd Hamburg Boston Denver 90123 56789 12345
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1-1 relationship types the names of multiple relationship types between the same two entity types must be unique female- customer male- customer current marriage 1 1 partial functions
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0-N and 1-N relationship types airport flt-schedule from 1 N partial function
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Mandatory 0-N and 1-N relationship types airport flt-schedule from 1 N total function
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N-M relationship types customer flt-instance reservation N M
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