Database Management Test 1

Which of the following is true according to the ABC Retailer ER diagram?

- a promotion can be associated with many products and it has to be associated with at least one product - each product belongs to exactly one brand

An ER diagram that contains two entities involved in two separate M:N relationships will be mapped as how many relations?

1

How many columns will a relation resulting from mapping the Entity Y have? Entity Y-> Attribute A, (dotted ellipse) Attribute B, Attribute C (0), Attribute D

3

How many columns will the table DRIVER have after mapping the ER diagram to tables?

3 or 4

How many tables will we get after mapping the Eaglerun Trucking Dispatcher ER diagram to tables?

4

Please select the right statement(s) about primary key in a relational database

At any time, no two rows of the same table have the same value for the primary key If a primary key is a composite attribute, no component of the composite attribute can be eliminated. Otherwise, the primary key cannot uniquely identify each row in a table. A primary key attribute (column) is not allowed to accept null value.

when transforming the following E-R diagram to relations, which of the following is correct? entity: employee identifier- E_ID attributes: DOB, Age (dotted ellipse) multivalued attribute: Hobbies

Employee (E_ID, DOB); Hobbies (E_ID, Hobbies)

A super key must be a candidate key in a table of a relational database.

False. A super key is not necessarily a candidate key. A candidate key must be a super key.

If a relation does not have a composite primary key, this relation must not have transitive dependency.

False. A transitive dependency is a functional dependency between two (or more) non-key attributes.

In RDBMS terminology, relations and relationships are exactly same. We can use them interchangeably.

False. In RDBMS terminology, relations are collection of attributes about a single subject such as students, orders, customers, etc. Relationships are linkage or logical way that data in one table is related to data in another table.

When we convert E-R diagrams to tables, we will only create one table for a unary many-to-many relationship.

False. We will create two tables for a unary many-to-many relationship: one for the entity, and the other for the many-to-many relationship.

In normalization, when we convert a table that is not in 1NF to a table in 1NF, we can remove partial functional dependency.

False. When we convert a table that is not in 1NF to a table in 1NF, we remove the repeating groups (muti-valued attributes).

The degree of a relationship describes the number of instances of one entity associated with another entity.

The cardinality of a relationship describes the number of instances of one entity associated with another entity.

1.1 Entity integrity rule states that no primary key attributes (or component of primary key attributes) can be null.

True

A determinant in a table is not necessarily a primary key

True

A secondary key is an attribute (or combination of attributes) used strictly for date retrieval purposes. A secondary key does not necessarily yield a unique outcome

True

If a relation is in 1NF, and this relation does not have any non-key attributes, this relation must be in 3NF.

True

When we convert E-R diagrams to tables, we must create an extra table for a composite attribute.

We create an extra table for multi-valued attribute rather than composite attribute.

employee works in department employee -> department (1:M) department -> employee (0:M)

a department can have more than one employee

diagram of unary relationship with person, zero to 1 cardinality

a person can marry at most one person

Which of the following anomalies result from a transitive dependency?

all! insertion, modification, deletion

Which of the following is typically found in the database metadata?

data types

An attribute that can be calculated from related attribute values is called a(n) ________ attribute.

derived

the attribute on the left-hand side of the arrow in a functional dependency is the:

determinant

The ____ states that no primary key attribute may be null

entity integrity rule

An attribute in a relation of a database that serves as the primary key of another relation in the same database is called a:

foreign key

relationship attributes may be necessary in a relationship of what type?

many-to-many

in the figure below, a student:

must be a graduate student, an undergrad student, a special student, or some other type of student

Which of the following is a possible type of relationship (maximum cardinality-wise)?

one-to-one

A functional dependency in which one or more non-key attributes are functionally dependent on part, but not all, of the primary key is called a ____ dependency

partial functional dependency

The completeness constraint in supertype/subtype relationships has the following possible rules:

partial specialization rule and total specialization rule

a rule that states that each foreign key value must match a primary key value in another relation or the foreign key value must be null

referential integrity rule

A relation that contains no multivalued attributes and has non-key attributes solely dependent on the primary key but contains transitive dependencies is in which normal form?

second

double line, overap rule diagram. this is an example of:

total specialization