CS 6400 Exam 2 prep
QUESTIONS AND VERIFIED
CORRECT ANSWERS
GRADED A+ [LATEST] 100%
GUARANTEED PASS
minimal superkey vs candidate key? - CORRECT ANSWER-They are the same
If R(A1, A2, A3,A4) is a relation and A1 and A2 are a primary key, how many super keys are there
- CORRECT ANSWER-1.) A1, A2
2.) A1, A2, A3
3.) A1, A2, A4
4.) A1, A2, A3, A4
If a relation's table in real life is ordered, should the contents of a relation be ordered as well? -
CORRECT ANSWER-Tuples are not to be ordered, although can be
How to map a N:M relationship from Relation 'R' to 'S'? - CORRECT ANSWER-1.) Foreign key of
relation 'R'
2.) Foreign key of relation 'S'
3.) Any relationship properties
How to map weak entity - CORRECT ANSWER-1.) Foreign key
2.) Weak key
3.) attributes of weak entity
, For mapping to relations, what 3 items you must look for - CORRECT ANSWER-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 - CORRECT
ANSWER-
Can a relation have a foreign key refering to another column in the same relation? - CORRECT
ANSWER-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'?
- CORRECT ANSWER-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? - CORRECT ANSWER-R; if it was Union all, then the output would
include duplicates
Does the Relation extension have to obey Relational intension? - CORRECT ANSWER-Absolutely;
items appended must obey the domain and data type subsets
3 types of constraints: - CORRECT ANSWER-inherent, schema, and application based
What is a result relation? - CORRECT ANSWER-result from a query
How to translate:
QUESTIONS AND VERIFIED
CORRECT ANSWERS
GRADED A+ [LATEST] 100%
GUARANTEED PASS
minimal superkey vs candidate key? - CORRECT ANSWER-They are the same
If R(A1, A2, A3,A4) is a relation and A1 and A2 are a primary key, how many super keys are there
- CORRECT ANSWER-1.) A1, A2
2.) A1, A2, A3
3.) A1, A2, A4
4.) A1, A2, A3, A4
If a relation's table in real life is ordered, should the contents of a relation be ordered as well? -
CORRECT ANSWER-Tuples are not to be ordered, although can be
How to map a N:M relationship from Relation 'R' to 'S'? - CORRECT ANSWER-1.) Foreign key of
relation 'R'
2.) Foreign key of relation 'S'
3.) Any relationship properties
How to map weak entity - CORRECT ANSWER-1.) Foreign key
2.) Weak key
3.) attributes of weak entity
, For mapping to relations, what 3 items you must look for - CORRECT ANSWER-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 - CORRECT
ANSWER-
Can a relation have a foreign key refering to another column in the same relation? - CORRECT
ANSWER-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'?
- CORRECT ANSWER-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? - CORRECT ANSWER-R; if it was Union all, then the output would
include duplicates
Does the Relation extension have to obey Relational intension? - CORRECT ANSWER-Absolutely;
items appended must obey the domain and data type subsets
3 types of constraints: - CORRECT ANSWER-inherent, schema, and application based
What is a result relation? - CORRECT ANSWER-result from a query
How to translate:
