Chapter 6

Suppose you have the following two tables where EmployeeNum is the primary key in both tables. What can you say about the EmployeeBuilding table?Employee (EmployeeNum, LastName, FirstName)EmployeeBuilding (EmployeeNum, BuildingName)FK EmployeeNum -> Employee a. The EmployeeBuilding table is a subtype of the Employee table. b. The EmployeeBuilding table is a supertype of the Employee table. c. The Employee table is a subtype of the EmployeeBuilding table. d. BuildingName is a subtype discriminator.

a. The EmployeeBuilding table is a subtype of the Employee table.

What does it mean when an entity has a minimum cardinality of one? a. The entity is required in the relationship. b. The entity is not required in the relationship. c. The entity should not be in the relationship as an attribute. d. The entity must be listed with all ones in the data fields.

a. The entity is required in the relationship.

After the information-level design is completed, what is the next step? a. The physical-level design b. The top-down design c. The bottom-up design d. The logical-level design

a. The physical-level design

What is an entity that can serve as the relationship between other entities called? a. composite entity b. complex entity c. complicated entity d. circular entity

a. composite entity

As soon as you have completed Steps 1 through 3 for a given user view, you can merge the results into the __________________ design.

cumulative

It is through foreign keys that you can create relationships among tables and enforce certain types of ____________________ constraints in a database.

integrity

The E-R model (also called ERM) uses diagrams to represent the high-level abstract and conceptual representation of data, along with entities, attributes, and ____________________.

relationships

Columns that are of interest strictly for the purpose of retrieval are known as ____________________.

secondary key

You create a many-to-many relationship by creating a new table whose primary key is the combination of the primary keys of the original tables.

true

The crucial issue in making the determination between a single many-to-many-to-many relationship and two (or three) many-to-many relationships is the ____. a. independence b. primary key c. redundancy d. primary index

a. independence

What is the term used in an E-R diagram that specifies the maximum number of entities that can participate in a relationship? a. maximum cardinality b. maximum entropy c. highest ratio d. highest entropy

a. maximum cardinality

Which type of key is usually an automatic numbering data type, such as the Access AutoNumber data type? a. surrogate b. artificial c. natural d. logical

a. surrogate

Which of the following is a set of requirements that is necessary to support the operations of a particular database user? a. user view b. user table c. user attribute d. user field

a. user view

Consider the following two tables where EmployeeNum is primary key in both tables. What is the result of combining the two tables?Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum)Employee (EmployeeNum, LastName, FirstName, Street, City, State, PostalCode) a. Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum, (Street, City, PostalCode) ) b. Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum, Street, City, State, PostalCode) c. Employee (EmployeeNum, LastName, FirstName, Street, City, State, PostalCode, WageRate, SocSecNum) d. Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum, EmployeeNum, LastName, FirstName, Street, City, State, PostalCode )

b. Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum, Street, City, State, PostalCode)

What does it mean when an entity has a minimum cardinality of zero? a. The entity has a mandatory role in the relationship. b. The entity is not required in the relationship. c. The entity should not be in the relationship as an attribute. d. The entity must be listed with all zeros in the data fields.

b. The entity is not required in the relationship.

When a DBMS cannot enforce data and access restrictions, how should they be enforced? a. by users when they are entering data using the DBMS b. by peripheral programs written to access the database c. by the operating system used to run the DBMS d. by technicians who monitor database usage

b. by peripheral programs written to access the database

In IDEF1X terminology, what is a subtype called? a. catalog b. category c. entity d. discriminator

b. category

As you design the user view, which aspect of the table are the properties of the entities you choose? a. rows b. columns c. data d. DBMS

b. columns

If an entity represented in a supertype table is not represented in the subtype table, what is this called in IDEF1X terminology? a. foreign key b. incomplete category c. subtype anomaly d. supertype discriminator

b. incomplete category

What type of key is also called a logical key? a. surrogate b. intelligent c. secondary d. synthetic

b. intelligent

On an E-R diagram, what does the number closest to the relationship represent? a. maximum entropy b. minimum cardinality c. midvalue ratio d. highest entropy

b. minimum cardinality

If each employee works in a single department and each department has several employees, what is the relationship between departments and employees? a. one-to-one b. one-to-many c. many-to-one d. many-to-many

b. one-to-many

When implementing the physical-level design, for secondary keys, you must ensure that it is possible to retrieve data rapidly based on a value of which key? a. primary b. secondary c. alternate d. foreign

b. secondary

What type of primary key is system-generated and is usually hidden from users? a. weak entity b. surrogate key c. natural key d. artificial key

b. surrogate key

What is the correct order of steps in the information-level design method?1. Normalize the tables.2. Represent the user view as a collection of tables.3. Merge the result into the cumulative design.4. Represent all keys. a. 1, 3, 2, 4 b. 2, 4, 3, 1 c. 2, 1, 4, 3 d. 1, 4, 2, 3

c. 2, 1, 4, 3

What is a column that you create for an entity to serve solely as the primary key and that is visible to users? a. synthetic key b. weak entity c. artificial key d. natural key

c. artificial key

What is a relationship that is necessary for identification? a. objectifying relationship b. merging relationship c. identifying relationship d. referential relationship

c. identifying relationship

What is an entity that does not require a relationship to another entity for identification? a. alternative entity b. foreign entity c. independent entity d. single entity

c. independent entity

____________________ refers to the number of items that must be included in a relationship.

cardinality

In IDEF1X, _______________ categories are represented by two horizontal lines below the category symbol.

complete

A(n) ____________________ is essentially both an entity and a relationship and is represented in an E-R diagram by a diamond within a rectangle.

composite entity

An alternative to the primary key of a table is listed with which abbreviation in DBDL? a. SK b. FK c. PK d. AK

d. AK

Convert the following table to first normal form:Branch (BranchNum, BranchName, (BookCode, Title, OnHand) ) where BranchNum is the primary key a. Branch (BranchNum, BranchName) where BranchNum is the primary keyBook (BookCode, Title) where BookCode is the primary key b. Branch (BranchNum, BranchName) where BranchNum is the primary key c. Book (BookCode, Title) where BookCode is the primary key d. Branch (BranchNum, BranchName, BookCode, Title, OnHand ) where BranchNum and BookCode make the primary key

d. Branch (BranchNum, BranchName, BookCode, Title, OnHand ) where BranchNum and BookCode make the primary key

If a many-to-many-to-many relationship is created when it is not appropriate to do so, how can the problem be corrected? a. by converting to 1NF b. by converting to 2NF c. by converting to 3NF d. by converting to 4NF

d. by converting to 4NF

Which of the following is an example of an enforcing restriction? a. ensuring each row has a primary key b. verifying there are no null values c. verifying there is at least one secondary key in each table d. ensuring values in foreign keys are legitimate

d. ensuring values in foreign keys are legitimate

In DBDL documentation, what element of a table is followed by an arrow pointing to the table identified by the element? a. columns b. alternate keys c. secondary keys d. foreign keys

d. foreign keys

Which of the following is used to improve performance in frequently used columns by maintaining a sort order but does not enforce constraints? a. surrogate key b. unique index c. artificial key d. nonunique index

d. nonunique index

When are nulls used? a. when a numeric value is zero b. when a character value is blank c. when a string contains a space d. when a value is inapplicable

d. when a value is inapplicable

When the existence of one entity depends on the existence of another related entity, there is an existence ____________________.

dependency

On an E-R diagram, ____________________ entities have rounded corners.

dependent

A subtype ____________________ is the specific attribute that determines the subtype-supertype relationship.

discriminator

A rectangle represents each _____________ in an E-R diagram.

entity

A design that supports all user views is called a constructive design.

false

A surrogate key is a primary key that consists of a column that uniquely identifies an entity.

false

After you have completed the first two steps for a given user view, you can merge the results into the cumulative design.

false

If each employee works in a single department, and each department has only one employee, the relationship between employees and departments is a one-to-many relationship.

false

If no unique identifier is available for an entity, you can go without one.

false

In a one-to-many relationship, the primary key of the "many" table becomes the foreign key of the "one" table.

false

In an entity-relationship diagram, rectangles represent foreign keys.

false

The first step in creating a user view is to normalize the collection of tables.

false

The first substep in representing the user view as a collection of tables is to determine entities and create a table for each.

false

When you combine third normal form tables, the result will always be in third normal form.

false

For each table, you must identify the primary key and any alternate keys, secondary keys, and ____________________ keys.

foreign

____________________ key restrictions determine the relationships between tables.

foreign

You can recognize entity subtypes by the fact the primary key is also a(n) ____________________.

foreign key

To obtain information about ____________________ dependencies you might ask users questions such as: "If you know a particular employee number, can you establish other information, such as employee name?"

functional

An entity with a minimum cardinality of one plays a(n) ____________________ role in the relationship.

mandatory

A(n) ____________________ is a special value that represents the absence of a value in a field.

null

An entity in a relationship with minimum cardinality of zero plays a(n) ____________________ role in the relationship.

optional

During the ____________________-level design, designers must consider the characteristics of the particular DBMS that the organization will use.

physical

When designing a database, you might find it helpful to design a ____________ form to obtain the required information from users.

survey

A foreign key is a column or collection of columns in one table that is required to match the value of the primary key for some row in another table, or be null.

true

A weak entity is an entity that depends on another entity for its own existence.

true

If you find that more than one table in your cumulative design has the same primary key, you should combine the tables to form a new table.

true

The basic relationships among entities are: one-to-many, many-to-many, and one-to-one.

true

The information-level design methodology is completed independently of any particular DBMS that the organization will ultimately use.

true

The simplest way to implement a one-to-one relationship is to treat it as a one-to-many relationship.

true

When combining third normal form tables, the resulting table will not be in third normal form when a column A in one user view determines a column B in a second user view, yet column A is not a column in the second user view.

true

When determining the primary key of a table you must decide what properties are required to uniquely identify an entity.

true

When the user views are not clearly defined, you should consider each stated requirement as a separate user view.

true