WGU - C192 - Lesson 5 - Relational
Algebra and Relational Calculus Exam
2026 Questions and Answers Graded A+
σpredicate (R) - Correct answer-The selection operation works on a single relation
R and defines a relation that contains only those tuples of R that satisfy the
specified condition (predicate).
Πa1 ... , an(R) - Correct answer-The projection operation works on a single relation
R and defines a relation that contains a vertical subset of R, extracting the values of
specified attributes and eliminating duplicates.
R u S - Correct answer-The union of two relations R and S defines a relation that
contains all the tuples of R, or S, or both R and S, duplicate tuples being eliminated
R and S must be union-compatible.
R - S - Correct answer-The set difference operation defines a relation consisting of
the tuples that are in relation R, but not in S. R and S must be union-compatible.
R ∩ S - Correct answer-The intersection operation defines a relation consisting of
the set of all tuples that are in both R and S. R and S must be union-compatible.
, R x S - Correct answer-The Cartesian product operation defines a relation that is
concatenation of every tuple of relation R with every tuple of relation S.
ρS(E) or ρS(a1, a2, . . . , an)(E) - Correct answer-The rename operation provides a
new name S for expression E, and optionally names the attributes as a1,
a2,..........,an.
R ⋈FS - Correct answer-The theta join operation defines a relation that contains
tuples satisfying the predicate F from the Cartesian product of R and S. The
predicate F is of the form R.ai θ S.bi, where θ may be one of the comparison
operators (<, ≤, >, ≥, =, ≠).
R ⋈ S - Correct answer-The natural join is an equijoin of the two relations R and S
over all common attributes x. One occurrence of each common attribute is
eliminated from the result.
R ⋊ S - Correct answer-The (left) Outer join is a join in which tuples from R that
do not have matching values in the common attributes of S are also included in the
result relation. Missing values in the second relation are set to null.
R ▹F S - Correct answer-The Semijoin operation defines a relation that contains
the tuples of R that participate in the join of R with S satisfying the predicate F.
Algebra and Relational Calculus Exam
2026 Questions and Answers Graded A+
σpredicate (R) - Correct answer-The selection operation works on a single relation
R and defines a relation that contains only those tuples of R that satisfy the
specified condition (predicate).
Πa1 ... , an(R) - Correct answer-The projection operation works on a single relation
R and defines a relation that contains a vertical subset of R, extracting the values of
specified attributes and eliminating duplicates.
R u S - Correct answer-The union of two relations R and S defines a relation that
contains all the tuples of R, or S, or both R and S, duplicate tuples being eliminated
R and S must be union-compatible.
R - S - Correct answer-The set difference operation defines a relation consisting of
the tuples that are in relation R, but not in S. R and S must be union-compatible.
R ∩ S - Correct answer-The intersection operation defines a relation consisting of
the set of all tuples that are in both R and S. R and S must be union-compatible.
, R x S - Correct answer-The Cartesian product operation defines a relation that is
concatenation of every tuple of relation R with every tuple of relation S.
ρS(E) or ρS(a1, a2, . . . , an)(E) - Correct answer-The rename operation provides a
new name S for expression E, and optionally names the attributes as a1,
a2,..........,an.
R ⋈FS - Correct answer-The theta join operation defines a relation that contains
tuples satisfying the predicate F from the Cartesian product of R and S. The
predicate F is of the form R.ai θ S.bi, where θ may be one of the comparison
operators (<, ≤, >, ≥, =, ≠).
R ⋈ S - Correct answer-The natural join is an equijoin of the two relations R and S
over all common attributes x. One occurrence of each common attribute is
eliminated from the result.
R ⋊ S - Correct answer-The (left) Outer join is a join in which tuples from R that
do not have matching values in the common attributes of S are also included in the
result relation. Missing values in the second relation are set to null.
R ▹F S - Correct answer-The Semijoin operation defines a relation that contains
the tuples of R that participate in the join of R with S satisfying the predicate F.
