Chapter 9

Data Design

1:1 (One-to-one)

When exactly one of the second entity occurs for each instance of the first entity

1:M (One-to-many)

When one occurrence of the first entity can be related to many occurrences of the second entity

Abbreviation Code

Alphabetic abbreviation

Absolute Date

The total number of days from some specific base date

Action Code

Indicates what action is to be taken with an associated item

Alphabetic Code

Uses alphabet letters to distinguish one item from another based on a category, an abbreviation, or an easy-to-remember value, called a mnemonic code

ASCII (American Standard Code for Information Interchange)

A data storage coding method used on most personal computers and workstations

Associative Entity

An entity that its own set of attributes and characteristics

Attribute

A single characteristic or fact about an entity

Audit Fields

Special fields within data records to provide additional control or security information

Audit Log Files

Record details of all access and changes to a file or database and can be used to recover changes made since the last backup

Backup

The process of saving a series of files or data copies to be retained for a specified period of time

Binary Storage Format

Offers efficient storage of numeric data

Bit

The smallest unit of data is one binary digit

Block Sequence Code

Cipher that uses blocks of numbers for different classifications

Byte

A group of eight bits, also called a character

Candidate Key

Any key that could serve as the primary key

Cardinality

Describes how instances of one entity relate to instances of another entity

Cardinality Notation

Code that shows relationships between entities

Category Codes

Ciphers that identify a group of related items

Character

A group of eight bits, also called a byte

Cipher Codes

Use of a keywords to encode a number

Clicks to Close

The average number of page views to accomplish a purchase or obtain desired information

Clickstream Storage

Recording web visitor behavior and traffic trends for later data mining

Code

A set of letters or numbers that represents a data item

Combination Key

A type of data validation check that is performed on two or more fields to ensure that they are consistent or reasonable

Common Field

An attribute that appears in more than one entity

Composite Key

When the primary key consists of a combination of fields; Also called the combination key, concatenated key, or multivalued key

Crow’s Foot Notation

A type of cardinality notation

Data Element

A single characteristic or fact about an entity; also called data item

Data Manipulation Language (DML)

Controls database operations, including storing, retrieving, updating, and deleting data

Data Mart

A specialized database designed to serve the needs of a specific department

Data Mining

Looking for meaningful patterns and relationships among data

Data Structure

A meaningful combination of related data elements that is included in a data flow or retained in a data store

Data Warehouse

An integrated collection of data that can support management analysis and decision making

Database Administrator (DBA)

Someone who manages a DBMS

Database Management System (DBMS)

A collection of tools, features, and interfaces that enables users to add, update, manage, access, and analyze data in a database

Derivation Code

Combining data from different item attributes, or characteristics, to build the code

Extended Binary Coded Decimal Interchange (EBCDIC)

A coding method used on mainframe computers and some high-capacity servers

Economy of Scale

How much money could be made in the future from the cost right now

Encryption

A process where data is coded so that only those with the required authorization can access the data

Entity

A person, place, or thing, or an event for which data is collected and maintained

Entity-Relationship Diagram (ERD)

A graphical model of the information system that depicts the relationships among system entities

Field

A single characteristic or fact about an entity

File

Each file or table contains data about people, places, things, events that interact with the information system

File-Oriented System

Stores and manages data in one or more separate files

First Normal Form (1NF)

A record is in 1NF if it does not contain a repeating group

Foreign Key

A field in one table that must match a primary key value in another table in order to establish the relationship between the two tables

Functionally Dependent

If Field X depends on the value of Y

International Organization for Standardization (ISO)

A network of national standards institutes from over a hundred countries working in partnership with international organizations, governments, industries, and business and consumer representatives

Java Database Connectivity (JDBC)

A standard that enables Java applications to exchange data with any database that uses SQL statements and ODBC-compliant

Key Fields

Used during the systems design phase to organize, access, and maintain data structures

Logical Record

Contains field values that describe a single person, place, thing, or event

Logical Storage

Refers to information as seen through a user’s eyes, regardless of how or where that information is organized or stored

Many-to-many Relationship (M:N)

Exists when one instance of the first entity can be related to many instances of the second entity, and one instance of the second entity can be related to many instances of the first entity

Market Basket Analysis

A type of analysis that can detect patterns and trends in large amounts of data

Middleware

Software that connects dissimilar applications and enables them to communicate and exchange data

Mnemonic Code

Ciphers using a specific combination of letters that are easy to remember

Non-key field

Any field that is not a primary key or a candidate key

Normalization

A process by which analysts identify and correct inherent problems and complexities in their record designs

Open Database Connectivity (ODBC)

An industry-standard protocol that makes it possible for software from different vendors to interact and exchange data

Orphan

An unassociated or unrelated record or field

Permissions

User-specific privileges that determine the type of access a user has to a database, file, or directory

Physical Storage

Information storage mechanism that is strictly hardware related, because it involves the process of reading and writing binary data to physical media

Primary Key

A field or combination of fields that uniquely and minimally identifies a particular member of an entity

Query by Example (QBE)

A language allows the user to provide an example of the data requested

Query Language

Allows a user to specify a task without specifying how the task will be accomplished

Record

A set of related fields that describes one instance, or member of an entity, such as one customer, one order, or one product. Also called a tuple

Recovery Procedure

Process for restoring data and restarting a system after an interruption

Referential Integrity

A set of rules that avoids data inconsistency and quality problems

Relational Database

A database in which tables are related by common fields, creating a unified data structure that provides improved data quality and access

Relational Model

Model used in relational databases

Repeating Group

A set of one or more fields that can occur any number of times in a single record, with each occurrence having different values

Scalability

A characteristic implying the system can be expanded, modified, or downsized easily to meet the rapidly changing needs of a business enterprise

Schema

The complete definition of a database, including descriptions of all fields, records, and relationships

Second Normal Form (2NF)

If all fields that are not part of the primary key are dependent on the entire primary key

Secondary

A field or combination of fields that can be used to access or retrieve records

Sequence Code

Numbers or letters assigned in a specific order

Significant Digit Code

Cipher that distinguishes items by using a series of subgroups of digits

Standard Notation Format

A representation that makes designing tables easier as it clearly shows a table’s structure, fields, and primary key

Structured Query Language (SQL)

A query language that allows PC users to communicate with servers and mainframe computers

Subschema

A view of the database used by one or more systems or users

Table

Each file or table contains data about people, places, things, or events that interact with the information system

Table Design

Specifies the fields and identifies the primary key in a particular table or file

Third Normal Form (3NF)

No non-key field is dependent on another non-key field

Tuple

A set of related fields that describes one instance

Unicode

A relatively recent coding method that represents characters as integers

Unified Modeling Language (UML)

A widely used method of visualizing and documenting software systems design

Unnormalized

A record that contains a repeating group, with each occurrence having different values

Y2K issue

A problem faced by many firms in the year 2000 because their computer systems used only two digits to represent the year