csce 4350 midterm UPDATED ACTUAL Questions
And Correct Answers
Terms in this set (109)
What does physical data Queries ignore indexes, physical storage can
independence mean? change without changing logical schema, users
don't need schema knowledge, and logical
changes never affect apps.
Which is NOT guaranteed in the No duplicate tuples, no tuple ordering, no attribute
relational model? ordering, atomic domains.
What are the truths of relational Procedural, has six basic operators, Turing
algebra? complete, equivalent in power to tuple/domain
relational calculus.
What does a candidate key mean? A proper subset also determines R, no proper
subset determines R, it's a minimal multivalued key,
it's a foreign key.
What does total participation mean? Every entity participates at least once, every entity
participates at most once, relationship must be 1:1,
entity must be weak.
What are the goals of normalization? Reduce redundancy, lossless decomposition, BCNF
always preserves dependencies, reduce anomalies.
, What is the BCNF condition for FD α is a candidate key, β is prime, α is a superkey,
α→β? α∩β≠∅.
What does 3NF allow? β⊆α, α is a superkey, each attribute in β−α is
contained in a candidate key, α∩β=∅.
What does MVD Y➙Z mean? Z determines Y, Z values associated with Y are
independent of other attributes, Y functionally
determines Z, Y is a superkey.
What does 1NF enforce? No partial dependencies, atomic attribute domains,
no transitive dependencies, lossless joins.
What is the relational algebra π_name(instructor 𝔚 teaches).
expression for names of instructors
who taught at least one course?
What are the options to list Projection, selection, union, set difference.
course_ids in Fall2017 or Spring2018?
What are the equivalent RA σ(p∧q)(r) = σ(p)(σ(q)(r)), σ(p∨q)(r) = σ(p)(r) × σ(q)(r),
expressions? π_A(σ_p(r)) = σ_p(π_A(r)) (always), r 𝔚_θ s = σ_θ(r×s).
What are the true statements Duplicates may appear in base relations, base
regarding duplicates? relations have no duplicates, projection removes
duplicates, joins never create duplicates.
What is the efficient query for π_name(σ dept_name='Physics' ∧ salary>90000
Physics instructors with salary > 90k, (instructor)).
names only?
What is the way to obtain only instructor × teaches.
instructors who taught?
And Correct Answers
Terms in this set (109)
What does physical data Queries ignore indexes, physical storage can
independence mean? change without changing logical schema, users
don't need schema knowledge, and logical
changes never affect apps.
Which is NOT guaranteed in the No duplicate tuples, no tuple ordering, no attribute
relational model? ordering, atomic domains.
What are the truths of relational Procedural, has six basic operators, Turing
algebra? complete, equivalent in power to tuple/domain
relational calculus.
What does a candidate key mean? A proper subset also determines R, no proper
subset determines R, it's a minimal multivalued key,
it's a foreign key.
What does total participation mean? Every entity participates at least once, every entity
participates at most once, relationship must be 1:1,
entity must be weak.
What are the goals of normalization? Reduce redundancy, lossless decomposition, BCNF
always preserves dependencies, reduce anomalies.
, What is the BCNF condition for FD α is a candidate key, β is prime, α is a superkey,
α→β? α∩β≠∅.
What does 3NF allow? β⊆α, α is a superkey, each attribute in β−α is
contained in a candidate key, α∩β=∅.
What does MVD Y➙Z mean? Z determines Y, Z values associated with Y are
independent of other attributes, Y functionally
determines Z, Y is a superkey.
What does 1NF enforce? No partial dependencies, atomic attribute domains,
no transitive dependencies, lossless joins.
What is the relational algebra π_name(instructor 𝔚 teaches).
expression for names of instructors
who taught at least one course?
What are the options to list Projection, selection, union, set difference.
course_ids in Fall2017 or Spring2018?
What are the equivalent RA σ(p∧q)(r) = σ(p)(σ(q)(r)), σ(p∨q)(r) = σ(p)(r) × σ(q)(r),
expressions? π_A(σ_p(r)) = σ_p(π_A(r)) (always), r 𝔚_θ s = σ_θ(r×s).
What are the true statements Duplicates may appear in base relations, base
regarding duplicates? relations have no duplicates, projection removes
duplicates, joins never create duplicates.
What is the efficient query for π_name(σ dept_name='Physics' ∧ salary>90000
Physics instructors with salary > 90k, (instructor)).
names only?
What is the way to obtain only instructor × teaches.
instructors who taught?
