CNIT 180 - Chapter 9

query languages

Allows a user to specify a task without specifying how the task will be accomplished. Some query languages use natural language commands that resemble ordinary English sentences

abbreviation code

Alphabetic abbreviation

common field

An attribute that appears in more than one entity. Common fields can be used to link entities in various types of relationships.

associative entity

An entity that has its own set of attributes and characteristics. Associative entities are used to link between many-to-many (M:N) relationships

ODBC (open database connectivity)

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

data warehouse

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

orphan

An unassociated or unrelated record or field. An orphan could be created if a customer order was entered in an order table where that customer did not already exist in the customer table. Referential integrity would prevent the creation of this orphan

nonkey field

Any field that is not a primary key or a candidate key is called a nonkey field.

significant digit code

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

category code

Cipher that identifies a group of related items.

block sequence code

Cipher that uses blocks of numbers for different classifications

mnemonic code

Ciphers using a specific combination of letters that are easy to remember; ex: LAX, ORD, MSP

cardinality notation

Code that shows relationships between entities.

derivation code

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

logical record

Contains field values that describe a single person, place, thing, or event. Application programs see a logical record as a set of fields, regardless of how or where the data is stored physically.

data manipulation language (DML)

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

file

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

table

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

1:1

Exactly one of the second entity occurs for each instance of the first entity.

second normal form (2NF)

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

data mining

Looking for meaningful patterns and relationships among data

third normal form (3NF)

No nonkey field is dependent on another nonkey field

sequence code

Numbers or letters assigned in a specific order; Contains no additional information other than an indication of the order of entry into a system.

recovery procedure

Process for restoring data and restarting a system after an interruption. Recovery procedures can be used to restore a file or database to its current state at the time of the last backup.

audit log files

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

clickstream storage

Recording web visitor behavior and traffic trends for later data mining use

logical storage

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

database administrator (DBA)

Someone who manages a database management system (DBMS). The DBA assesses overall requirements and maintains the database for the benefit of the entire organization rather than a single department or user.

multivalued key

Sometimes it is necessary for a primary key to consist of a combination of fields. In that case, the primary key is called a combination key, composite key, concatenated key, or multivalued key

candidate key

Sometimes it is possible to have a choice of fields or field combinations to use as the primary key. Any field that could serve as a primary key is called a candidate key

audit fields

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

table design

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

ASCII

Stands for American Standard Code for Information Interchange, a data storage coding method used on most personal computers and workstations; 8-bit

EBCDIC

Stands for Extended Binary Coded Decimal Interchange Code, a coding method used on mainframe computers and some high-capacity servers; 8-bit

file-oriented system

Stores and manages data in one or more separate files

clicks to close

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

schema

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

functionally dependent

The field X is said to be functionally dependent on the field Y if the value of X depends on the value of Y.

economy of scale

The inherent efficiency of high-volume processing on larger computers. Database design allows better utilization of hardware. If a company maintains an enterprise-wide database, processing is less expensive using a powerful mainframe server instead of using several smaller computers.

backup

The process of saving a series of file or data copies to be retained for a specified period of time. Data can be backed up continuously, or at prescribed intervals.

bit

The smallest unit of data is one binary digit.

absolute date

The total number of days from some specific base date. To calculate the number of days between two absolute dates, subtract one date from the other

cipher code

Use of a keyword to encode a number

key fields

Used during the systems design phase to organize, access, and maintain data structures. The four types of key fields are primary keys, candidate keys, foreign keys, and secondary keys

permissions

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

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.

M:N

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

1:M

When one occurrence of the first entity can be related to many occurrences of the second entity, but each occurrence of the second entity can be associated with only one occurrence of the first entity

tuple

A set of related fields that describes one instance, or member of an entity ;Might have one or dozens of fields, depending on what information is needed.

referential integrity

A set of rules that avoids data inconsistency and quality problems; A type of validity check

data mart

A specialized database designed to serve the needs of a specific department; Includes only the data that users in that department require to perform their jobs.

JDBC (Java database connectivity)

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

market basket analysis

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

crow's foot notation

A type of cardinality notation

subschema

A view of the database used by one or more systems or users. A subschema defines only those portions of the database that a particular system or user needs or is allowed to access.

International Organization for Standardization (ISO)

A network of national standards institutes from 140 countries working in partnership with international organizations, governments, industry, business, and consumer representatives. The ISO acts as a bridge between public and private sectors

Y2K issue

A problem faced by many firms in the year 2000 because their computer systems used only two digits to represent the year; most dates now use a four-digit format for the year (YYYYMMDD).

normalization

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

SQL (Structured Query Language)

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

first normal form (1NF)

A record does not contain a repeating group (a set of data items that can occur any number of times in a single record).

unnormalized

A record that contains a repeating group, which means that a single record has multiple occurrences of a particular field, with each occurrence having different values

Unicode

A relatively recent coding method that represents characters as integers. Unlike EBCDIC and ASCII, which use eight bits for each character, Unicode requires 16 bits per character, which allows it to represent more than 65,000 unique characters.

standard notation format

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

code

A set of letters or numbers that represents a data item. Codes can be used to simplify output, input, and data formats.

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.

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.

relational database

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

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

secondary key

A field or combination of fields that can be used to access or retrieve records. Secondary key values are not unique

primary key

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

binary storage format

A format that offers efficient storage of numeric data.

entity-relationship diagram (ERD)

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

character

A group of eight bits

byte

A group of eight bits; a character. A set forms a field, which is an individual fact about a person, place, thing, or event

query by example (QBE)

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

relational model

A model used in relational databases. The relational model was introduced during the 1970s and became popular because it was flexible and powerful.

action code

Indicates what action is to be taken with an associated item; ex: X to exit the program

physical storage

Information storage mechanism that is strictly hardware-related, because it involves the process of reading and writing binary data to physical media, such as a hard drive, flash drive, or DVD.