Chapter 9 - Designing Databases

Which of the following choices are used in a unary one-to-one (1:1) relationship?

- Adding the primary key of A as a foreign key of B. - Adding the primary key of B as a foreign key of A. - Both of the above.

Which of the following have properties that distinguish from a relation?

- Entries in cells are simple. - Entries in columns are from the same set of values. - Each row is unique. - The sequence of columns can be interchanged without changing the meaning or use of the relation. - The rows may be interchanged or stored in any sequence.

Which of the following choices are to provide a specific file for the file organization?

- Fast data retrieval. - High throughput for processing transactions. - Efficient use of storage space. - Protection from failures or data loss. - Minimal need for reorganization. - Accommodation for growth. - Security from unauthorized use.

Which of the following are secondary memory?

- Hard Disks - Magnetic Tape - SSD - Flash Drive

Which of the following choices are used in a data type?

- Length - Coding Scheme - Number of Decimal Places - Minimum and Maximum Values - Other Parameters

Which of the following information should be included while designing a physical file and database?

- Normalized relations. - Definitions of each attribute. - Descriptions of where and when data are used. - Expectations or requirements for response time and data integrity. - Descriptions of technologies used for implementing the files and database so that the range of required decisions and choices for each is known.

Which of the following are the purposes of logical and physical databases?

- Structure the data in stable structures that are not likely to change over time and have minimal redundancy. - Develop a logical database design that reflects the actual requirements in which it exists in forms and reports. - Develop a logical database from which can do physical database design. - Translate a relational model into a technical file and database design. - Choose data storage technologies.

Which of the following conditions apply in 2NF?

- The primary key consists of only one attribute. - No nonprimary key attributes exist in the relation. - Every nonprimary key attribute is functionally dependent on the full set of primary key attributes.

Which of the following should you check to make sure that the primary key satisfies the following two properties?

- The value of the key must uniquely identify every row in the relation. - They key should be nonredundant.

Which of the following steps are a key to logical database modeling and design?

1. Develop a data model for each known user interface. 2. Combine normalized data requirements into one logical database. 3. Translate the E-R data model into normalized data requirements. 4. Compare consolidated logical database with the translated E-R model and produce a final logical database model for the application.

What are the four objectives when selecting a data type?

1. Minimize storage space 2. Represent all possible values. 3. Improve data integrity. 4. Support all data manipulations.

What is a primary key that is identified as a whole?

2NF

What are normal key attributes that do not depend on each other?

3NF

How does the functional dependence represent by?

Arrow

What places the primary key of the entity on the side of the relationship as a foreign key in the relation for the entity on the many side?

Binary 1:N Relationship

What is a relationship in an E-R diagram represented by adding the primary key attribute of the entity on one side of the relationship as a foreign key in the relation that is on the many side of a relationship?

Binary One-to-Many

What places the primary key of either entity in the relation for the other entity or do it for both entities?

Binary or Unary 1:1 Relationship

What is a field that can be derived from other database fields?

Calculated (or Computed or Derived) Field

What key is it when it includes the primary key of the entity on which this weak entity depends?

Composite Primary Key

What is an example of referential integrity?

Cross-referencing between relations.

What is a coding scheme recognized by system software for representing organizational data?

Data Type

What are storage formats also called?

Data Types

Date and time values for the years, 100 to 9999. Eight bytes of storage space is required.

Date/Time

What is the value of a field that will assume unless an explicit value is entered for that field?

Default Value

What does the procedure for representing relationships depend on?

Degree

What is the process of splitting or combining normalized relations into physical tables based on affinity of use of rows and fields?

Denormalization

What are attributes from decomposing the relation into new relations called?

Determinants

What is the smallest unit of named application data recognized by system software?

Field

What is a technique used for physically arranging the records of a file?

File Organization

What are individual and groups of records that can be stored, retrieved, and updated rapidly also called?

File Organizations

What is an attribute that appears as a nonprimary key attribute in one relation and as a primary key attribute in another relation?

Foreign Key

What is 2NF also called?

Full Functional Dependency

What is a particular relationship between two attributes?

Functional Dependency

What is the address for each row is determined using an algorithm?

Hashed File Organization

What is a single attribute that is used for two or more different attributes?

Homonym

What is a primary key that is underlined called?

Identifier Attribute

What is a table used to determine the location of rows in a file that satisfy some condition?

Index

What are the rows that are stored either sequentially or nonsequentially, and an index is created that allows software to relocate individual rows?

Indexed File Organization

What is a pattern of codes that restricts the width and possible values for each position in a field?

Input Mask

Lengthy text or combinations of text and numbers. One byte of storage is required for each character used.

Memo

What is the step where the relations can be combined to renormalize them and to remove redundancy?

Merge the Relations

What is 3NF also called?

No Transitive Dependency

What is the way to build a data model that has properties of simplicity, nonredundancy, and minimal maintenance?

Normalization

What is the step where the relations need to be normalized to make them well-structured?

Normalize the Relations

What is a description of associated database requirements called?

Normalized Relations

What is the process of converting complex data structures into simple, stable data structures?

Normalizing

What is a special field value, distinct from 0, blank, or any other value, that indicates that the value for the field is missing or otherwise unknown?

Null Value

Numeric data used for mathematical calculations.

Number

What are units called in a disk that can be read or written in one machine operation?

Pages

What is a named set of table rows stored in a contiguous section of secondary memory?

Physical File

What is a named set of rows and columns that specifies the fields in each row of the table?

Physical Table

What is a field of data that can be used to locate a related field or row of data?

Pointer

What is an attribute whose value is unique across all occurrences of a relation?

Primary Key

What limits both numeric and alphabetic data?

Range Control

What is a foreign key that references the primary key values of that same relation?

Recursive Foreign Key

What is a foreign key in a relation that references the primary key values of that same relation?

Recursive Relation

What is a unary relationship between the instances of a single entity type?

Recursive Relationship

What is an integrity constraint specifying that the value of an attribute in one relation depends on the value of the same attribute in another relation?

Referential Integrity

What creates a relation with primary keys and nonkey attributes?

Regular Entity

What is a named, two-dimensional table of data?

Relation

What is data represented as a set of related tables or relations?

Relational Database Model

What is the step where each entity type in the E-R diagram becomes the relation?

Represent Entities

What is the step where each relationship in an E-R diagram must be represented in the relational database design?

Represent Relationships

What is a relation for which every nonprimary key attribute is functionally dependent on the whole primary key.

Second Normal Form

What is one or more combination of fields for which more than one row may have the same combination of values?

Secondary Key

What is grouping attributes from the logical database model into physical records also called?

Selecting a Stored Record (Data Structure)

What are rows in the file that are stored in sequence according to a primary key value?

Sequential File Organization

What are two or more different names, but the same meaning?

Synonym

In what phase of the SDLC is designing a database under?

Systems Design

Text or combinations of text and numbers, as well as numbers that don't require calculation.

Text

What is a relation that is in second normal form and has no functional dependencies between two or more non primary key attributes?

Third Normal Form

What is a functional dependency between nonprimary key attributes is also called?

Transitive Dependency

How many may an attribute be dependent on?

Two or more.

What is the last step in logical databases where you describe merging relations?

View Integration

What creates a relation with a composite primary key and nonkey attributes?

Weak Entity

What is a relation that contains a minimum amount of redundancy and allows users to insert, modify, and delete the rows without errors or inconsistencies?

Well-Structured Relation (Table)