Database Glossary
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Access window
The program window that appears when you start
the program.
Ad-hoc reporting
The ability to access information from a database to meet information
requirements as required. One-off requests not satisfied by pre-set
reporting.
Agent
An application that searches the data and sends an alert when a
particular pattern is found.
Aggregations
Information stored in a data warehouse in a summarized form. Instead
of recording the date and time each time a certain product is sold,
the data warehouse could store the quantity of the product sold
each hour, each day, or each week. Aggregations are used for two
primary reasons:
- To save storage space. Data warehouses can get large. The use
of aggregations greatly reduces the space needed to store data.
- To improve the performance of business intelligence tools. When
queries run faster they take up less processing time and the users
get their information back more quickly.
Some data warehouses store both the detailed information and aggregated
information. This takes even more space, but gives users the possibility
of looking at all the details while still having good query performance
when looking at summaries.
Some systems use aggregations for historical data. Perhaps detailed
data is kept on-line for a year. After that the detailed data is kept
in a less accessible, permanent storage format, and only the aggregated,
summary data is kept on-line.
Aggregations are often created as the sum of the individual records.
You can also have aggregations for count, distinct count, maximum
value, and minimum value.
Alert
A message that is sent automatically by a computer system when a
certain situation occurs.
Application
A piece of software designed to meet a specific purpose.
Attribute
A single data item related to a database object. The database schema
associates one or more attributes with each database entity.
Also known as: field, column.
Example: In the following database table, the attributes are Name,
EmpID, Extension
|
Name
|
EmpID
|
Extension
|
| Andy Mullard |
100 |
1230 |
| Kathy Smith |
115 |
1255 |
| William Thompson |
170 |
1258 |
B
Business intelligence tools
Software that enables business users to see and use large amounts
of complex data.
C
Candidate key
A combination of attributes that can be uniquely used to identify
a database record. Each table may have one or more candidate keys.
One of these candidate keys is selected as the table primary key.
Examples: There are a large number of candidate keys in the sample
table below. Some of these are SIN, Phone Extension,
Name, SSN, and Name, Age, SIN. Note that Age
is not a candidate key in this case because Amy and Elizabeth share
the same age.
|
Name
|
Age
|
SIN
|
Phone Extension
|
| Hillary Peterson |
35 |
270-266-485 |
1111 |
| John Willow |
22 |
270-459-221 |
2222 |
| Sophie McDowell |
25 |
270-778-496 |
3333 |
| Chris Wonder |
40 |
270-886-785 |
4444 |
| Tamara Shill |
31 |
270-996-115 |
5555 |
Cardinality
In set theory, cardinality refers to the number of members in the
set. When specifically applied to database theory, the cardinality
of a table refers to the number of rows (or tuples) contained in
a table.
Chief Information Officer (CIO)
The senior executive in a company responsible for information management
and for delivering IT services.
Clickstream data
Data regarding web browsing.
Client/Server architecture
A type of network in which computer processing is distributed among
many individual PCs (clients) and a more powerful, central computer
(server). Clients can share files and retrieve data stored on the
server.
Collaborative software
Groupware, such as Lotus Notes or Microsoft Exchange.
Common field
A field that appears in more than one table
when you want to relate them and is connecting the records in the
separate tables.
Composite key
In some cases two or more fields might be
needed to function as the primary key. In these cases the primary
key is referred to us as composite key.
D
Data
A series of facts or statements that may have been collected, stored,
processed and/or manipulated but have not been organized or placed
into context. When data is organized, it becomes information. Information
can be processed and used to draw generalized conclusions or knowledge.
Database
A collection of tables. It also often includes forms for entering
data, rules for checking and validating data that has been entered,
and the format for creating informative reports from the data in
the database.
Database window
This appears when you open a database in Access.
Data cleansing
The process of manipulating stored data to make it more aligned.
Implies eliminating duplication, correcting spelling and removing
null fields.
Data-based knowledge
Knowledge derived from data through the use of Business Intelligence
Tools and the process of Data Warehousing.
Data mart
A database that has the same characteristics as a data warehouse,
but is usually smaller and is focused on the data for one division
or one workgroup within an enterprise.
Also Known As: Local Data Warehouse or Datamart.
Data migration
The process of physically transmitting data from one environment
to another.
Data mining
The use of automated data analysis techniques to uncover previously
undetected relationships among data items. Data mining often involves
the analysis of data stored in a data warehouse. Three of the major
data mining techniques are regression, classification and clustering.
Data model
The description of the contents of a database. It includes tables
and the relationship between them.
Data quality
The suitability of data for different requirements. When constructing
and populating a database the data quality must be checked to ensure
that it meets the needs of all the applications.
Data scrubbing
Removing errors and inconsistencies from data being imported into
a data warehouse.
Datasheet view
Shows a table's contents as a datasheet in
rows and columns, similar to a table or spreadsheet. Each row is
a separate record in the table, and each column contains the field
values for one field in the table.
Data transformation
The modification of data as it is moved into the data warehouse.
Data type
Determines what field values you can enter for
the field and what other properties the field will have. Field size
is assigned to text fields and number fields.
Data warehouse
A data warehouse is a centralized database that captures information
from various parts of an organization's business processes. This
information can later be analyzed to determine predictive relationships
through the use of data mining techniques.
Data warehousing management
The on-going supervision of the data warehousing process.
Database Management System (DBMS)
The software that is used to store, access, and manage data. It
is a software program that lets you create databases and then manipulate
data in the databases. Most of today's database management systems
are called relational database management systems where data is
organized as a collection of tables.
Decision support system (DSS)
A computer system designed to assist an organization in making decisions.
Dimension
The separation of data according to different view. A logical designation
of related information that applies a hierarchy for access and reporting.
Domain
The set of all allowable values that attribute may assume.
Drill down and drill up
The ability to move between levels of the hierarchy when viewing
data with an OLAP browser.
- Drill down - Changing the view of the data to a greater level
of detail.
- Drill up - Changing the view of the data to a higher level of
aggregation.
E
Enterprise resource planning
An integrated system of operation applications combining logistics,
production, distribution, contract and order management, sales forecasting,
and financial and HR management.
Entity
A single object about which data can be stored. It is the "subject"
of a table. Entities and their interrelationships are modeled through
the use of entity-relationship diagrams.
Electronic Data Interchange (EDI)
Electronic transmission of documents through point-to-point connections
using a set of standard forms, messages and data elements; this
can be via leased lines, private networks or the Internet.
F
Fact table
In a star schema, the central table which contains the individual
facts being stored in the database.
Field
A single characteristic or attribute of a person, place, object,
event, or idea. It is the most basic structural unit of a database.
It is a container for a piece of data. In most cases, only a single
logical piece of data fits in each field.
Field value
The specific value, or content, of a field.
Flat file
A data file that contains records with no structured relationships.
Additional knowledge is required to interpret these files such as
the file format properties. Modern database management systems used
a more structured approach to file management (such as one defined
by the Structured Query Language) and therefore have more complex
storage arrangements.
Foreign key
When you include the primary key from one table
as a field in a second table to form a relationship between the
two tables, it is called a foreign key in the second table.
Form
An object you use to maintain, view and print records in a database.
You can perform these functions with tables and queries, but forms
can present data in customized and useful ways to facilitate database
data entry and/or retrieval operations. The form displays one record
at a time. A database developer/administrator usually designs a
form which can then be used by personnel without any specific database
skills to perform repetitive tasks.
Front end
Tools that enable users to interact with underlying application
processes or more complex programs through a familiar, easy-to-use
interface.
G
Gateway
This is the interface between different computer network, (usually
translates from one network protocol to another).
Granularity
The level of detail of the facts stored in a data warehouse.
H
Hardware
The magnetic, mechanical and electrical components of a computer
and its peripheral devices.
Hierarchy
Organization of data into a logical tree structure.
I
Index
A database feature used for locating data quickly within a table.
Indexes are defined by selecting a set of commonly searched attribute(s)
on a table and using the appropriate platform-specific mechanism
to create an index.
Example: Personnel information may be store in a Human Resource department's
employee table. Clerks find that they often search the table for employees
by last name but get slow query responses. Defining an index on the
table consisting of the last name attribute would speed up these queries.
Information technology (IT)
The hardware and software used to process information.
K
Key
A field that contains a unique identifier for each row in a data
table. Even though each individual record represents a separate
piece of data, some of those records may look identical. A key provides
a completely unambiguous way to distinguish between distinct records,
and more importantly, serves as a pointer to a particular record
in the table. In many cases, data table keys are constructed by
simply adding an additional field to function as the key.
L
Legacy system
A computer system that's been around for a while.
Level
The hierarchies in dimensions have levels which can be used to view
data at various levels of detail.
Examples:
- A Time dimension could have levels for Year, Quarter, Month,
and Day.
- A Product dimension could have levels for Product Family, Product
Category, Product Subcategory, and Product Name.
- A Customer Geography dimension could have levels for Region,
Country, District, State, City and Neighborhood.
Local database warehouse
A database that has the same characteristics as a data warehouse,
but is usually smaller and is focused on the data for one division
or one workgroup within an enterprise.
M
Mainframe
The central processing unit of a large computer, usually receiving
input from a number of terminals.
Member
One of the data points for a level of a hierarchy of a dimension.
Example: Some of the members of the Month level of the Time dimension
are January, February, March, and April.
Metadata
A term that literally means "data about data." This term refers
to information about data itself -- perhaps the origin, size, formatting
or other characteristics of a data item. In the database field,
metadata is essential to understanding and interpreting the contents
of a data warehouse.
Microprocessors
Complex electronic circuits that comprise a computer's central information
processing unit.
Multidimensional database management system (MDBMS)
A database management system that organizes data multidimensionally.
N
Non-volatile
Data that does not change.
Normalization
The process of structuring relational database schema such that
most ambiguity is removed. The stages of normalization are referred
to as normal forms and progress from the least restrictive (First
Normal Form) through the most restrictive (Fifth Normal Form). Generally,
most database designers do not attempt to implement anything higher
than Third Normal.
O
Object tab
Appears when you open a database in Access. It
is a window that contains seven object tabs: tables, queries, forms,
reports, pages, macros and modules.
OLAP (on-line analytical processing)
The use of computers to analyze an organization's data.
OLAP browser
A tool used for multidimensional (OLAP) browsing.
OLAP system
Term that is used as a synonym for datawarehousing system.
OLTP (online transaction processing)
The use of computers to run the on-going operation of a business.
P
Primary key
A field or a collection of fields, whose values
uniquely identify each record in a table.
Program
A set of digitally coded definitions and instructions that enables
a computer to perform a particular task.
Protocol
The language that one computer uses to communicate with another.
Q
Query
A question you ask about the data stored in a database. It can be
built by the Wizard or also custom-made. The records are currently
listed in order by the primary key field but you also sort them
by specifying other criterias as well. Many database management
systems use the (Structured Query Language) standard query format.
R
Record or a row
The set of field values. The fields in a record provide a complete
description of each item in a collection. A record is a unique instance
of data about an object or event.
Relationships
The connections between records in different data tables are provided
by relationships.
-
One-to-Many Relationship: The most common
relationship between two tables. In this situation, precisely
one record in data table A is related to a number of records
in data table B. The primary key of table A is inserted as a
field into table B where it serves as a foreign key. Relationships
between tables are always made through keys.
-
One-to-One Relationship: Each record in one
table is linked to one and only one record in another table.
In many cases, one of the tables is set of data about a subset
of the entities in the main table.
-
Many-to-Many Relationship: Table design rounds
out the possible ways of designing data relationships. In some
situations, multiple entries in a data table are related to
multiple entries in another data table. The classic example
is a database of classes and students. Each class consists of
many students and each student can take many classes, so in
designing a database to track student and class information,
a many-to-many design is necessary.
The distinguishing characteristic of many-to-many relationships between
two tables is that they require a third table to make the relationship.
Simply putting the key from one table into the other table would result
in a lot of duplicated information, so a linking table is used to
connect the tables. The linking table simply stores the primary key
from one table with the primary key of its related entry from the
second table, along with any other information unique to the relationship.
Relational database management system (RDBMS)
A Database Management System is based on relational theory with
a collection of related tables. Most modern Database Management
Systems (Oracle, Sybase, Microsoft SQL Server) are relational databases.
These databases support a standard language - SQL (Structured Query
Language).
Replication
The physical copying of data from one database to another.
Report
A formatted printout (or screen display) of the contents
of one or more tables in a database. It allows you the greatest
flexibility for formatting printed output.
S
Scale, scalable, and scalability
Having to do with the ability of a computer system or a database
to operate efficiently with larger quantities of data. Scalability
is often discussed in situations when multiple processors are joined
together. The system scales well (or is scalable) if doubling the
number of processors also doubles the speed at which the system
performs its tasks. The extra work involved in coordinating larger
systems usually prevents them from being fully scalable - so that
going from one to two processors would increase the total speed
by less than a factor of two.
Schema
The logical organization of data in a database.
Shared dimension
In Microsoft Analysis Services, a dimension used by more than one
cube.
Slowly changing dimensions (SCD)
A dimension that has levels or attributes that are changing on an
occasional basis.
Software
The programs that are run on a computer system.
Star schema (business definition)
A method of organizing information in a data warehouse that allows
the business information to be viewed from many perspectives. The
star is a picture of the way the data is being stored. The basic
factual information is in the middle of the star. The points of
the star represent various perspectives from which the factual information
can be viewed.
Structured query language (SQL)
An industry-standard language used for manipulation of data in a
relational database. The major SQL commands of interest to database
users are Select, Insert, Join and Update.
Summary tables
Tables used to store summarized or aggregated data.
Supercomputer
An extremely powerful computer; designed to deal with large amounts
of data at very high speed, often used for military or scientific
tasks.
T
Table
Acollection of fields that describe a person, place, object, event,
or idea. The formal name given to the group of records that contain
the elements of the collection.
Time-variant data
Data that is identified with a particular time period. Time-variant
is one of the original defining characteristics of a data warehouse.
X
XML
XML is the eXtensible Markup Language -- a system created to define
other markup languages. For this reason, it can also be referred
to as a metalanguage. XML is commonly used on the Internet to create
simple methods for the exchange of data among diverse clients.
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