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CS6400 Exam Prep Questions and Answers Verified 100% Correct
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CS6400 Exam Prep Questions and Answers Verified 100% Correct
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CS6400 Exam Prep Questions and Answers Verified100% Correct
If a relation's table in real life is ordered, should the contents of a relation be ordered as well? -
✔✔Tuples are not to be ordered, although can be
How to map a N:M relationship from Relation 'R' to 'S'? - ✔✔1.) Foreign key of relation 'R'
2.) Foreign key of relation 'S'
3.) Any relationship properties
How to map weak entity - ✔✔1.) Foreign key
2.) Weak key
3.) attributes of weak entity
For mapping to relations, what 3 items you must look for - ✔✔1.) entities
2.) relationships (N:M mainly)
3.) multi-value attributes
If you want to identify from two Relations ('R' and 'S') all the possible combinations - ✔✔
Can a relation have a foreign key refering to another column in the same relation? - ✔✔Yes,
typically the primary key (primary key can be more than one attribute, but only one primary key
can exist per relation)
When determining how many tuples will be the output of a 'left outer join' or 'right outer join'?
- ✔✔1.) If foreign key has all the items in the opposing table's primary key, then the number
of tuples will match the larger table's
2.) If the column with the foreign has some missing items from the original primary key, it will
be count of tuples in the large relation + missing foreign key items.
, What is the output of R U R? - ✔✔R; if it was Union all, then the output would include
duplicates
Does the Relation extension have to obey Relational intension? - ✔✔Absolutely; items
appended must obey the domain and data type subsets
3 types of constraints: - ✔✔inherent, schema, and application based
What is a result relation? - ✔✔result from a query
How to translate:
'''
Employee(e) and (∃x)(Works_On(w) and Project(p)
''''
into universal quantifier notation - ✔✔Employee(e) and (∀x)(Not(Works_on(w) OR NOT
(Project(p))
What is the key/primary key in a relation formed by a multi value attribute? - ✔✔The foreign
and the attribute
What's another way a relation can be declared? - ✔✔A declaration and assertion
Whats a transaction? - ✔✔executing program that performs db operations
If a record contains a key that is a referenced in another table and you try to delete it, what are
the options? - ✔✔1.) Restrict
'or'
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