CS6400 - Exam 3 UPDATED ACTUAL
Questions and CORRECT Answers
Natural Join - CORRECT ANSWER✔✔- The result of this is the set of all combinations of
tuples in R and S that are equal on their common attribute names. A special case of an
equijoin.
Left Outer Join - CORRECT ANSWER✔✔- A construct operator which results in the set of
all combinations of tuples in R and S that are equal on their common attribute names, in
addition (loosely speaking) to tuples in R that have no matching tuples in S.
Insert - CORRECT ANSWER✔✔- A basic SQL operation in which new records are added to
a table.
Delete - CORRECT ANSWER✔✔- A basic SQL operation in which existing records are
removed from a table.
Update - CORRECT ANSWER✔✔- A basic SQL operation in which existing records are
changed in a table.
Select * - CORRECT ANSWER✔✔- A basic SQL operation in which existing records are
chosen from a table.
Select Distinct - CORRECT ANSWER✔✔- A basic SQL operation in which only unique
existing records are chosen from a table.
Intersect - CORRECT ANSWER✔✔- Set operator which includes all tuples that are in both
R and S.
Union - CORRECT ANSWER✔✔- Set operator which includes all tuples that are either in R
or in S or in both R and S. Duplicates are removed.
Union All - CORRECT ANSWER✔✔- set operator which includes all tuples that are either
in R or in S or in both R and S. Duplicates are not removed.
, Count(*) - CORRECT ANSWER✔✔- SQL function which returns the number of rows that
matches the specified criteria.
Group By - CORRECT ANSWER✔✔- SQL operator which rolls up the result set by one or
more columns.
Equijoin - CORRECT ANSWER✔✔- A theta join using the equality operator
Difference / Minus - CORRECT ANSWER✔✔- Set operator which includes all tuples that
are in R but not in S
Theta Join - CORRECT ANSWER✔✔- A construct operator which allows for arbitrary
comparison relationships (such as >=)
Inner Join - CORRECT ANSWER✔✔- Requires each row in the two joined tables to have
matching column values.
Cartesian Product - CORRECT ANSWER✔✔- A construct operator which results in the set
of all combinations of tuples in R and S
Reflexive Inference Rule - CORRECT ANSWER✔✔- If Y is a subset of X, then X -> Y. i.e.
EG -> G
Augmentation Inference Rule - CORRECT ANSWER✔✔- If X -> Y, then XZ -> YZ for any
Z i.e. E->A, therefore EG->AG
Transitive Inference Rule - CORRECT ANSWER✔✔- If X -> Y and Y -> Z, then X -> Z,
i.e. B->E, E->A, therefore B->A
Decomposition Inference Rule - CORRECT ANSWER✔✔- If X -> YZ then X -> Y and X -
>Z
Questions and CORRECT Answers
Natural Join - CORRECT ANSWER✔✔- The result of this is the set of all combinations of
tuples in R and S that are equal on their common attribute names. A special case of an
equijoin.
Left Outer Join - CORRECT ANSWER✔✔- A construct operator which results in the set of
all combinations of tuples in R and S that are equal on their common attribute names, in
addition (loosely speaking) to tuples in R that have no matching tuples in S.
Insert - CORRECT ANSWER✔✔- A basic SQL operation in which new records are added to
a table.
Delete - CORRECT ANSWER✔✔- A basic SQL operation in which existing records are
removed from a table.
Update - CORRECT ANSWER✔✔- A basic SQL operation in which existing records are
changed in a table.
Select * - CORRECT ANSWER✔✔- A basic SQL operation in which existing records are
chosen from a table.
Select Distinct - CORRECT ANSWER✔✔- A basic SQL operation in which only unique
existing records are chosen from a table.
Intersect - CORRECT ANSWER✔✔- Set operator which includes all tuples that are in both
R and S.
Union - CORRECT ANSWER✔✔- Set operator which includes all tuples that are either in R
or in S or in both R and S. Duplicates are removed.
Union All - CORRECT ANSWER✔✔- set operator which includes all tuples that are either
in R or in S or in both R and S. Duplicates are not removed.
, Count(*) - CORRECT ANSWER✔✔- SQL function which returns the number of rows that
matches the specified criteria.
Group By - CORRECT ANSWER✔✔- SQL operator which rolls up the result set by one or
more columns.
Equijoin - CORRECT ANSWER✔✔- A theta join using the equality operator
Difference / Minus - CORRECT ANSWER✔✔- Set operator which includes all tuples that
are in R but not in S
Theta Join - CORRECT ANSWER✔✔- A construct operator which allows for arbitrary
comparison relationships (such as >=)
Inner Join - CORRECT ANSWER✔✔- Requires each row in the two joined tables to have
matching column values.
Cartesian Product - CORRECT ANSWER✔✔- A construct operator which results in the set
of all combinations of tuples in R and S
Reflexive Inference Rule - CORRECT ANSWER✔✔- If Y is a subset of X, then X -> Y. i.e.
EG -> G
Augmentation Inference Rule - CORRECT ANSWER✔✔- If X -> Y, then XZ -> YZ for any
Z i.e. E->A, therefore EG->AG
Transitive Inference Rule - CORRECT ANSWER✔✔- If X -> Y and Y -> Z, then X -> Z,
i.e. B->E, E->A, therefore B->A
Decomposition Inference Rule - CORRECT ANSWER✔✔- If X -> YZ then X -> Y and X -
>Z
