ISTM 320 Exam 2

What does a physical ERD fulfill that a logical ERD does not?

A physical ERD takes into consideration all of the technological and organizational issues of a database. It goes into a greater level of detail than logical diagrams and includes data types.

What is an entity?

An entity can be a person, place, or thing.

Relationships between two instances of two different entity types are called _________ relationships.

Binary

What is the difference between logical and conceptual ERDs?

Conceptual ERDs are not concerned with implementation details, rather they focus on the organizational structure of the data. Logical diagrams are more concerned with the details of entities and relationships between entities. Logical diagrams are somewhat concerned with technological implementation.

If you have a many-to-many relationship, you should _______________.

Create an associative entity

When Dr. Gomillion looks at his class roster at the beginning of the semester, the only identifying information of the students in the class are their UINs. He doesn't find this helpful, so he modifies the database design to show their names as well. In doing so, he is likely ___________ the database.

Denormalizing

A(n) ________ is an attribute whose value can be computed from related attribute values

Derived attribute

On a logical ERD, what is a good way to identify primary keys and foreign keys?

Double-underline primary keys, underline foreign keys.

During logical database design, you must account for every data element on a system input or output form or report and on the ________

E-R diagram

The most common format used for data modeling is ________ diagramming

Entity-relationship

What is needed for an ERD to be in first normal form?

Every entity must have a primary key?

Relations are the connections between entities

False. Relations are tables. Relationships are the connections between entities.

A binary one-to-many (1:N) relationship in an E-R diagram is represented by adding the primary key attribute (or attributes) of the entity on the one side of the relationship as a(n) ________ in the relation that is on the many side of the relationship

Foreign key

What's the point of normalization?

Get rid of redundancy, which wastes disk space and may lead to inconsistency in the data.

There are 200 MIS students at Mays. In a relational database, each student could be considered a(n) ________ of the "Student" entity.

Instance

In logical database modeling and design, we combine normalized data requirements from all user interfaces into one consolidated logical database model; this step is called view

Integration

In logical database modeling and design, we combine normalized data requirements from all user interfaces into one consolidated logical database model; this step is called view ________

Integration

______________ attributes can have more than one value.

Multi-valued

A(n) ________ is an attribute that may take on more than one value for each entity instance

Multi-valued attribute

A(n) ________ is a specification that indicates how many objects participate in a given relationship

Multiplicity

What is needed for an ERD to be in second normal form?

Must be in first normal form. Every non-primary key attribute must be dependent on the WHOLE primary key.

What is needed for an ERD to be in third normal form?

Must be in second normal form. Non-primary key attributes cannot be functionally dependent on other non-primary key attributes.

For the purpose of this class, should you use multi-valued attributes on logical diagrams?

No. You should use weak entities.

The result of normalization is that every ________ key attribute depends upon the whole primary key

Non-primary

________ is a process for converting complex data structures into simple, stable data

Normalization

Maximum cardinalities can be either __________ or __________.

One, many

Minimum cardinalities can be either 0, which is considered to be ___________, or 1, which is considered to be ___________.

Optional, required

Entities do not capture processes, they capture ________________.

Outputs

Logical and ________ database design is typically performed in parallel with other systems design

Physical

Each entity type in the E-R diagram becomes a relation. The identifier of the entity type becomes the ________ of the relation, and other attributes of the entity type become non-primary key attributes of the relation

Primary key

Each instance of an entity is uniquely identified by its ______________.

Primary key

For the purpose of this class, what are two things that every entity MUST have?

Primary key and attributes

A(n) ________ is an operation that does not have any side effects; it accesses the state of an object but does not alter the state

Query operation

One purpose of database design is to structure the data in stable structures, called normalized tables, that are not likely to change over time and that have minimal ________

Redundancy

What kind of DBMS are we using in this class?

Relational database

Define relationships.

Relationships are when instances of different entities are related to each other with PK/FK pair

A(n) ________ is an attribute that must have a value for every entity instance

Required attribute

In a data table, each student is stored in a ______, and each attribute is stored in a ______.

Row, column

A common mistake many people make when they are just learning to draw E-R diagrams, especially if they already know how to do data flow diagramming, is to confuse data entities with ________ and relationships with data flows

Sinks

A well-structured relation is a relation that contains a minimum amount of redundancy and that allows users to insert, modify, and delete the rows without error or inconsistencies and is also known as a ________

Table

Relationships between three instances of three different entity types are called _________ relationships.

Ternary

An ERD has an attribute called "Name" for both the Customer entity and Employee entity. What is wrong with this, and how can it be fixed?

The attribute is not descriptive enough, and could easily be confused when deployed. A good way to fix this would be calling them CustomerName and EmployeeName.

A primary key is an attribute

True

A relation is a named, ________-dimensional table of data. Each relation (or table) consists of a set of named columns and an arbitrary number of unnamed rows

Two

Relations are _____________ data tables.

Two-dimensional

A recursive relationship is also known as a ________ relationship

Unary

Relationships between two instances of the same entity types are called _________ relationships.

Unary

Which relation is created by placing the primary key of either entity in the relation for the other entity or by doing this for both entities?

Unary 1:1 relationship

For the purpose of this class, each attribute can only have one value. If multiple values are needed, you must create a ___________.

Weak entity

For the purpose of this class, should you use associative entities on logical diagrams?

Yes. You should use associative entities