CPSC 440 Exam 1

¡Supera tus tareas y exámenes ahora con Quizwiz!

What is an associateive entity?

An entity that associates the instances of one or more entity types and contains attributes specific to the relationships.

What is a Partial Dependency?

one or more nonkey attributes are functionally dependent on part, but not all, of the primary key.

What is a composite key?

primary key that consists of more than one attribute

What is the Second Normal Form?

relation that contains no multivalued attributes and has nonkey attributes solely dependnet on the primary key but contains transitive dependencies.

What is Referential Integrity Constraint?

rule that states that each foreign key value must match a primary key value in the other relation.

Cardinality Constraint

specifies the number of instances of one entity that can be associated with each instance of another entity.

When did E. F. Codd develop the relational model?

1970s

Employee (zero or many) -- (one or many) Department Describe this relationship.

A department can have one or more than one employee.

What is a Unary relationship?

A relationship between the instances of a single entity type is called a(n) _____ relationship.

What is a Ternary relationship?

A simultaneous relationship among the instances of three entity types.

What is the determinant?

Attribute on the left-hand side of the arrow in a functional dependency.

In SQL, what is used to make table definitions?

CREATE TABLE _______

A rule that CANNOT be violated by database users is called a _______

Constraint

A person, place, an object, an event or concept about which the organization wishes to maintain data is called _____

Entity

T or F: A ternary relationship is equivalent to three binary relationships

False

A student can attend five classes, each with a different professor. Each professor has 30 students. The relationship of students ot professors is a ______ relationship.

Many-to-many

What is the Entity Integrity Rule?

No primary key attribute may be null

T or F: A cascading delete removes all records in other tables associated with the record to be deleted.

True

T or F: A data model is a graphical system used to caputre the nature and relationships among data.

True

T or F: A multivalued attribute may take on more than one value for a particular entity instance

True

T or F: A physical schema contains the specifications of how data from a conceptual schema are stored in a computer's secondary memory.

True

T or F: A relational database establishes the relationships between entities by means of a common field.

True

T or F: a single occurrence of an entity is called an entity instance

True

What is an identifying relationship?

a relationship between a weak entity type and its owner.

What is a composite attribute?

an attribute that can be broken down into smaller parts.

What is a derived attribute?

an attribute that can be calculated form related attribute values.

What is a required attribute?

an attribute that must have a value for every entity (or relationship) instance.

What is a weak entity?

an entity type whose existence depends on another entity type.

What is a Partial Nonkey Dependency?

between two or more nonkey attributes.

When a regular entity type contains a multivalued attribute, one must:....

create two new relations, one containing the multivalued attribute


Conjuntos de estudio relacionados

Economics Chapter Question Ch1-3

View Set

Exam 1 Chapters 1,2,3 Top Gunder

View Set

Abeka 7th Grade History Appendix Quiz V

View Set

The Constitution and American Political Principles

View Set

CH 8: Families [Part 3], CH 8: Families [Part 2], CH 8: Families [Part 1], CH 7: Moral Development [Part 3], CH 7: Moral Development [Part 2], CH 7: Moral Development [Part 1], CH 6: Sexuality [Part 3], CH 6: Sexuality [Part 2], CH 6: Sexuality [Part...

View Set