Database Ch. 6
30. An alternative to the primary key of a table is listed with the ____ abbreviation in DBDL.
AK
. Convert the following table to first normal form: Branch (BranchNum, BranchName, (BookCode, Title, OnHand) )
Branch (BranchNum, BranchName, BookCode, Title, OnHand )
___________________ refers to the number of items that must be included in a relationship.
Cardinality
The properties of the entities you choose as you design the user view will become the ____ in the appropriate tables.
Columns
Which of the following shows sample DBDL documentation for the Employee table?
Employee (EmployeeNum, LastName, FirstName, Street, City, State, PostalCode, WageRate, SocSecNum, DepartmentNum) AK SocSecNum SK LastName FK DepartmentNum→Department
Combining the following two tables would result in ____. Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum) Employee (EmployeeNum, LastName, FirstName, Street, City, State, PostalCode)
Employee (EmployeeNum, LastName, FirstName, WageRate, SocSecNum, DepartmentNum, Street, City, State, PostalCode)
.The second step in creating a user view is to represent the user view as a collection of tables.
False
A design that supports all user views is called a constructive design.
False
A weak entity is a column or collection of columns that could have been chosen as a primary key, but was not.
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 E-R diagram, a dashed line represents an identifying relationship and a solid line represents a nonidentifying relationship.
False
In an entity-relationship diagram, rectangles represent foreign keys.
False
The first step in creating a user view is to normalize the tables.
False
There are two types of primary keys that you can use in your database design.
False
When you combine third normal form tables, the result will always be in third normal form.
False
____________________ key restrictions determine the relationships between tables.
Foreign
The style of E-R diagram used in the text is ____________________.
IDEF1X
The type of information collected on the survey form that describes how data is updated is ____.
Processing information
____ means that an entity has a minimum cardinality of zero.
The entity is not required in the relationship.
____ means that an entity has a minimum cardinality of one
The entity is required in the relationship.
After the information-level design is completed, ____ is the next step.
The physical-level design
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
Careful planning in the early stages of the normalization process will usually avoid the need to consider fourth normal form.
True
In DBDL, you represent a table by listing all columns and then underlining the primary key.
True
Nulls are used when a value is either unknown or inapplicable.
True
The basic relationships among entities are: one-to-many, many-to-many, and one-to-one.
True
The information-level design methodology involves representing the individual user view as a collection of tables, refining them to eliminate any problems, and then merging them into a cumulative design.
True
The primary key is a unique identifier.
True
The use of an "m" and an "n" in an E-R diagram indicates a many-to-many relationship.
True
When provided with a user view or some sort of stated requirement, you must develop a collection of tables that will support it.
True
When you use an E-R diagram to represent a database, it visually illustrates all the information listed in the DBDL.
True
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
A column that you create for an entity to serve solely as the primary key and that is visible to users is called a(n) ____.
artificial key
In the ____________________ design method, specific user requirements are synthesized into a design.
bottom-up
A subtype is called a(n) ____ in IDEF1X terminology.
category
In IDEF1X, the ____ is the symbol for category.
circle
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 entity that exists to implement a many-to-many relationship is called a(n) ____.
composite entity
An entity-relationship (E-R) model is an approach to representing data in a(n) ____________________.
database
On an E-R diagram, ____________________ entities have rounded corners.
dependent
A weak entity corresponds to the term ____________________.
dependent entity
In the standard E-R diagrams, relationships are drawn as ____, with lines connecting the entities involved in relationships.
diamonds
When the existence of one entity depends on the existence of another related entity, there is a(n) ____________________.
existence dependency
For each table, you must identify the primary key and any alternate keys, secondary keys, and ____________________ keys.
foreign
You can recognize entity subtypes by the fact the primary key is also a(n) ____________________.
foreign key
If a many-to-many-to-many relationship is created when it is not appropriate to do so, the conversion to ____ normal form will correct the problem.
fourth
To obtain information about ____________________ you might ask users questions such as: "If you know a particular employee number, can you establish other information, such as employee name?"
functional dependencies
A relationship that is necessary for identification is called a(n) ____.
identifying relationship
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 ____.
independence
An entity that does not require a relationship to another entity for identification is called a(n) ____.
independent entity
It is through foreign keys that you can create relationships among tables and enforce certain types of ____________________ constraints in a database.
integrity
A natural key is also called a(n) ____ key.
intelligent
One way to indicate a one-to-many relationship is to place a crow's foot at the ____________________ end of the relationship.
many
On an E-R diagram, the number closest to the rectangle represents ____ cardinality.
maximum
On an E-R diagram, the number closest to the relationship represents ____ cardinality.
minimum
A(n) ____ is a primary key that consists of a column that uniquely identifies an entity, such as a person's Social Security number.
natural key
A relationship that is not necessary for identification is called a(n) ____________________ relationship.
nonidentifying
A(n) ____________________ is a special value that represents the absence of a value in a field.
null
If each employee works in a single department and each department has only one employee, the relationship between employees and departments is ____.
one-to-one
During the ____________________ design, designers must consider the characteristics of the particular DBMS that the organization will use.
physical-level
When implementing the physical-level design, for secondary keys, you must ensure that it is possible to retrieve data rapidly on the basis of a value of the ____ key.
secondary
Columns that are of interest strictly for the purpose of retrieval are known as ____________________.
secondary keys
Independent entities have ____ in an E-R diagram
square corners
When a DBMS creates a(n) ____ key, it is usually an automatic numbering data type, such as the Access AutoNumber data type.
surrogate
A(n) ____ is a system-generated primary key that is usually hidden from users.
surrogate key
When designing a database, you might find it helpful to design a(n) ____ to obtain the required information from users.
survey form
The ____________________ design method begins with a general database design that models the overall enterprise and repeatedly refines the model to achieve a design that supports all necessary applications.
top-dowm
Complete categories are represented by ____ line(s) below the category symbol.
two
A set of requirements that is necessary to support the operations of a particular database user is known as a(n) ____.
user view
An entity that depends on another entity for its own existence is called a(n) ____________________.
weak entity dependent entity