Cs 6400 Exam 2 Questions With Answers

CS 6400 Exam 2 QUESTIONS WITH
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ANSWERS

Entity type ET with single value property - CORRECT ANSWERS
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✔✔relation ET has B as an attribute |\ |\ |\ |\ |\ |\




Entity type ET with identifying property A - CORRECT ANSWERS
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✔✔relation ET there will be an attribute A that is a primary key
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Entity ET with composite C, made up D and E - CORRECT
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ANSWERS ✔✔Relation only includes D and E, C is lost
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Relation model is inherently: - CORRECT ANSWERS ✔✔flat!
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Entity ET with identifying property A and multi-value property F -
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CORRECT ANSWERS ✔✔For each F a brand new relation is
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created, called ET-F. insert identifying property so combination of
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A and F is a composite key in ET-F
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1:1 relational mapping - CORRECT ANSWERS ✔✔B in ET1 is a
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foreign key to B in ET2. or A in ET2 is a foreign key to A in ET1.
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both are acceptable.
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1:1 mandatory relationship - CORRECT ANSWERS ✔✔A in ET2
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(where the relationship is mandatory) is a foreign key to A in ET1
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, 1:N relationship mapping - CORRECT ANSWERS ✔✔A in ET2 (the
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many side) is a foreign key to A in ET1 (the one side). A in ET1 is
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unique for every single value of B
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N:M Relation - CORRECT ANSWERS ✔✔There needs to be a
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relation,R, for the relationship that has a foreign key for each
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attribute. A in R is a foreign key to A in ET1 and B in R is a
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foreign key to B in ET2 |\ |\ |\ |\ |\




Identifying relationship R to weak Entity ET2 - CORRECT |\ |\ |\ |\ |\ |\ |\ |\ |\


ANSWERS ✔✔ET2 requires a reference to ET1, A in ET2 is a |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\


foreign key to A in ET1. A and B in combination are required to
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define ET2 |\




Mandatory/disjoint relation for super/sup type - CORRECT |\ |\ |\ |\ |\ |\ |\


ANSWERS ✔✔ET1 and ET2 are disjoint so every ET distance has
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an A and B and every instance is hooked to ET1 or ET2. ET1 will
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inherit A and B and have C, ET2 will also and have D. only create
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a relation for ET1 and ET2, not ET. ET1 is A, B, C; ET2 is A, B, D.
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Mandatory Overlap relation - CORRECT ANSWERS ✔✔Every |\ |\ |\ |\ |\ |\ |\


instance of ET is an instance of ET1, ET2, or both. A in ET1 and
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ET2 are foreign keys to A in ET. ET is A,B. ET1 is A, C. ET2 is A, D
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non-mandatory overlap relation - CORRECT ANSWERS ✔✔A in |\ |\ |\ |\ |\ |\ |\ |\


ET1 and ET2 are foreign keys to A in ET
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non-mandatory/disjoint - CORRECT ANSWERS ✔✔A in ET1 and |\ |\ |\ |\ |\ |\ |\ |\


ET2 are foreign keys to A in ET
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