MC A relation is in 3 NF if it satisfies 2 NF and... no primary key of R is transitively dependent on a prime attribute type. incorrect no nonprime attribute type of R is transitively dependent on the primary key. correct no non-primary key of R is transitively dependent on a prime attribute type. incorrect no prime attribute type of R is transitively dependent on the primary key. incorrect
MC A relation is in 3 NF if it satisfies 2 NF and... no primary key of R is transitively dependent on a prime attribute type. incorrect no nonprime attribute type of R is transitively dependent on the primary key. correct no prime attribute type of R is transitively dependent on the primary key. incorrect no non-primary key of R is transitively dependent on a prime attribute type. incorrect
MC Given the following (normalized) relational model (primary keys underlined; foreign keys in italics):
EMPLOYEE(SSN, ENAME, EADDRESS, SEX, DATE_OF_BIRTH, SUPERVISOR, DNR)
SUPERVISOR: foreign key, refers to SSN in EMPLOYEE, NULL value not allowed
DNR: 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 key, refers to DNR in DEPARTMENT, NULL value not allowed
WORKS_ON(SSN, PNR, HOURS)
SSN: foreign key, refers to SSN in EMPLOYEE, NULL value not allowed
PNR: foreign key, refers to PNR in PROJECT, NULL value not allowed
Which statement is NOT CORRECT? A department has always exactly one manager. incorrect Every project is always assigned to exactly one department. incorrect Every employee must be always supervised by exactly one other employee. incorrect An employee must work in the same department than he/she manages. correct
MC Consider the following ER model for a course administration.
Which statement is NOT CORRECT? When mapping the ER relationship type organizes between Course and Session to the relational model, the primary key "cnb" of the Course relation will be included as a NOT NULL foreign key in the Session relation. The 4 cardinalities of this ER relationship type can be perfectly mapped to the relational model. incorrect Both the ER and the relational model cannot enforce that a teacher can only teach sessions of courses for which he/she is qualified. incorrect When mapping the ER relationship type teaches between Session and Teacher to the relational model, a new relation needs to be introduced. The 4 cardinalities of this ER relationship type can be perfectly mapped to the relational model. correct When mapping the ER relationship type enrollment between Session and Student to the relational model, a new relation needs to be introduced. The 4 cardinalities of this ER relationship type can be perfectly mapped to the relational model. incorrect
MC A relation is in 3 NF if it satisfies 2 NF and... no prime attribute type of R is transitively dependent on the primary key. incorrect no non-primary key of R is transitively dependent on a prime attribute type. incorrect no primary key of R is transitively dependent on a prime attribute type. incorrect no nonprime attribute type of R is transitively dependent on the primary key. correct
MC The following relational model represents a HRM system of a consultancy firm. The primary keys are underlined while foreign keys are in italic font.
Consultant (ConsultantID, Date of Birth, Expertise)
Assigned_to (ConsultantID, ProjectID)
ConsultantID refers to ConsultantID in Consultant
ProjectID refers to ProjectID in Project
Project (ProjectID, Description, Type, Company)
Company refers to Name in Company
Company (Name, Location)
Suppose a new consultant is hired and immediately assigned to a new training project at a new firm and to 2 other, already existing projects. How many rows (tuples) must be added to the database to reflect this change? 6 correct 1 incorrect 5 incorrect 3 incorrect
MC Which statement is CORRECT? Every relation must have a foreign key. incorrect A relation cannot have more than 1 foreign key. incorrect A foreign key of a relation A cannot refer to the primary key of the same relation A. incorrect A foreign key can be NULL. correct
MC Consider a data model for the Olympics storing information about countries and athletes. There is a 1-N relationship type between country and athlete and an athlete always has to belong to exactly 1 country. A relational data model containing only 1 table leads to: Unnecessary replication of data about countries. correct Unnecessary replication of data about athletes and countries. incorrect No unnecessary replication of data. incorrect Unnecessary replication of data about athletes. incorrect
MC The following relational model represents a HRM system of a consultancy firm. The primary keys are underlined while foreign keys are in italic font.
Consultant (ConsultantID, Date of Birth, Expertise)
Assigned_to (ConsultantID, ProjectID)
ConsultantID refers to ConsultantID in Consultant
ProjectID refers to ProjectID in Project
Project (ProjectID, Description, Type, Company)
Company refers to Name in Company
Company (Name, Location)
Suppose a new consultant is hired and immediately assigned to a new training project at a new firm and to 2 other, already existing projects. How many rows (tuples) must be added to the database to reflect this change? 6 correct 5 incorrect 1 incorrect 3 incorrect
MC A relation is in 3 NF if it satisfies 2 NF and... no non-primary key of R is transitively dependent on a prime attribute type. incorrect no primary key of R is transitively dependent on a prime attribute type. incorrect no prime attribute type of R is transitively dependent on the primary key. incorrect no nonprime attribute type of R is transitively dependent on the primary key. correct