If a relation schema is in 3nf, it is in BCNF.
True/False
Foreign key values can...
If a relation schema is in 3nf, it is in BCNF.
True/False
Foreign key values can be null.
True/False
In a table there is exactly one candidate key, but there can be
multiple super keys.
True/False
Any candidate key is a super key
True/False
The primary key of a relation may have more than one attribute.
However, a foreign key of a relation must have only
one attribute.
True/False
Given relation R1, where R1 contains N1 tuples and a...
In SQL, Integrity Control on DELETE CASCADE means:
a) To make users unable to delete a...
In SQL, Integrity Control on DELETE CASCADE means:
a) To make users unable to delete a parent row if there are
matching dependent rows
b) When a parent row is deleted, all dependent rows will be
deleted
c) When a parent row is deleted, set the foreign key value to
null in all the dependent rows
d) All of the above
TRUE or FALSE
1. Reliability refers to the consistency of a psychological
tool, whereas, validity refers...
TRUE or FALSE
1. Reliability refers to the consistency of a psychological
tool, whereas, validity refers to the accuracy of a psychological
tool.
2. When an clinician asks a client a prepared set of questions
during a session, the clinician conducts a structured
interview.
3. Psychodynamic clinicians mainly use intelligence tests with
clients.
4. A client who takes the Minnesota Multiphasic Personality
Inventory (MMPI) who perceives that they have multiple and frequent
health issues should score high on the Hypochondriasis...
1. Suppose StudentID is the primary key of one table (e.g., the
Students table) and the...
1. Suppose StudentID is the primary key of one table (e.g., the
Students table) and the foreign key of another table (e.g., the
Top10DesiredJobs table). If you can’t enforce the referential
integrity relationship between these two tables, what might be the
cause?
Select one:
a. The values of the primary key column are referenced by the
values of the foreign key column.
b. The foreign key contains duplicate data.
c. The foreign key column contains values that do not exist...
Determine whether the given statement is true or false. Explain
your answer.
(a) If R is...
Determine whether the given statement is true or false. Explain
your answer.
(a) If R is an antisymmetric relation, then R is not
symmetric.
(b) If John Jay College was founded in 1997, then the moon is
made of cheese. (
c) ∀x∃y(x divides y) where the domain of discourse for both
variables is {2, 3, 4, 5, 6}.
(d) ∃x∀y(x divides y) where the domain of discourse for both
variables is {2, 3, 4, 5, 6}.
(e) ∀n(3n ≤...
Here are SQL declarations for three tables R, S, and T:
CREATE TABLE R(e INT PRIMARY...
Here are SQL declarations for three tables R, S, and T:
CREATE TABLE R(e INT PRIMARY KEY, f INT);
CREATE TABLE S(c INT PRIMARY KEY, d INT REFERENCES R(e) ON DELETE CASCADE);
CREATE TABLE T(a INT PRIMARY KEY, b INT REFERENCES S(c) ON DELETE CASCADE);
Suppose R(e,f) contains tuples
(1,0), (2,4), (3,5), (4,3), and (5,7).
Suppose S(c,d) contains tuples
(1,5), (2,2), (3,3), (4,5), and (5,4).
Suppose T(a,b) contains tuples
(0,2), (1,2), (2,3), (3,4), and (4,4).
As a result of the...
1.Consider the following (normalized) relational model (primary
keys
are underlined, foreign keys are in italics). EMPLOYEE(SSN,...
1.Consider the following (normalized) relational model (primary
keys
are underlined, foreign keys are in italics). EMPLOYEE(SSN,
ENAME, EADDRESS, SEX,
DATE_OF_BIRTH, SUPERVISOR, DNR)
S U P E R V I S O R : foreign key refers to SSN in EMPLOYEE,
NULL value allowed
D N R : foreign key refers to DNR in DEPARTMENT, NULL value not
allowed
DEPARTMENT(DNR, DNAME, DLOCATION, MGNR) MGNR: foreign key refers
to SSN in EMPLOYEE, NULL
value not allowed
PROJECT(PNR, PNAME, PDURATION, DNR)
DNR: foreign...