 |
| A |
| Attributes |
Attributes
are the record elements contained within tables e.g. a
customer table would contain information such as name,
address etc. They are technically known as "attributes" of
the entity "customer". |
| Access |
Microsoft
Access is one of many databases that offers a flexible
environment for developers and users. It makes use
of the familiar Microsoft Office interface and allows for
integration with larger-scale enterprise databases such
as Microsoft's SQL Server and Oracle. Due to the
familiar Microsoft format, this is a good starting point
when learning about database creation |
| B [ Back to top ] |
| Boyce-Codd
Normal Form |
A
relation is in Boyce-Codd Normal Form (BCNF) if every determinant
is a candidate key. |
| C [ Back to top ] |
| Candidate
Key |
A
candidate key is a combination of attributes which allows
the identification of a database record. |
| Column |
The
tables within a database are made up of individual columns
relating to the attributes of the object. |
| D [ Back to top ] |
| Data |
Data
consists of a series of unorganised facts or statements
that have been collected, stored, processed and/or manipulated. |
| Database |
A
database is a collection of information organised into
inter-related tables of data, to allow users to reach
the required information with ease
|
| E [ Back to top ] |
| Entity |
The
word ‘entity’ as it relates to databases can simply be
defined as the general name for the information that is
to be stored within a single table e.g. a "customer" table. |
| Entity-Relationship
Diagram (ERD) |
An
ERD is essentially a graphical representation of the database
structure. |
| F [ Back to top ] |
| First
Normal Form |
To
be in First Normal Form, each field in a table contains
different information and should therefore contain no repeating
attributes. For example, in an employee list, each table
would contain only one birthdate field. |
| Foreign
Key |
A
Foreign key forms the basis of a 1:M relationship between
two tables. The Foreign key can be found within the "M" table,
and maps to the Primary key found in the "1" table. |
| Flat
File |
Flat
files are data files that contain records but do not
have any structured relationships. Additional knowledge
is required to interpret these files such as the file
format properties.
|
| Form |
A
database form can be used to facilitate database data entry
and/or retrieval operations and is usually developed for
a user without any specific database skills. |
| Fourth
Normal Form |
To
be in Fourth Normal Form, a relation must first be in
Boyce-Codd Normal Form. Additionally, a given relation
may not contain more than one multivalued attribute. |
| Functional
Dependency |
A
functional dependency occurs when one attribute determines
another attribute. |
| G [ Back to top ] |
| |
|
| H [ Back to top ] |
| Hierarchical
database |
A
kind of database management system that links records
together like a family tree such that each record type
has only one owner, e.g. an order is owned by only
one customer. Hierarchical structures were widely used
in the first mainframe database management systems.
However, due to their restrictions, they often cannot
be used to relate structures that exist in the real
world. |
| I [ Back to top ] |
| Incremental
Updates |
Consist
of records that are to be "merged" with the
data already in a database. When a database integrates
data into its own, it checks for unique record ID's.
e.g. if a book with an ID already in the database is
found, the database overwrites the old record with the
new. |
| Index |
An
Index is a database feature used for locating data quickly
within a table. For example, Employee information may
be stored in a Human Resource department's Employee table.
To search the table for Employees by last name may result
in a slow query response. Defining an "Index" on
the table consisting of the last name attribute would
speed up these queries. An
index is a link between one table and another, it allows
for rapid access to the rows of a table based on the
values of one or more columns in another table. |
| Information |
Data
that has been processed in such a way that it can increase
the knowledge of the person who receives it. Information
is the output, or finished goods, of information systems.
Information is also what individuals start with before
it is fed into a Data Capture transaction processing
system. |
| Input
Mask |
An
input mask helps to control the values that are entered
into a field and might include dashes, spaces, or parentheses. Input
masks may be automatically applied to certain fields,
such as phone numbers or zip codes. |
| Instance |
A
technical term used to refer to a database in a way that
includes all of its technical components (the disk files
that hold the tables, the part of the computer memory
allocated for the database and the software that is necessary
to manage the database). |
| J [ Back to top ] |
| Join |
Join
operators compare two or more tables (or views) by specifying
a column from each, comparing the values in those columns
row by row, and concatenating rows in which the comparison
is true. |
| Journal
File |
A
file that contains update activity for rollback and data
recovery purposes. Examples of update activity are commit
checkpoints, as well as before and after operational
database images. A journal file may be used to construct
snapshot information for the data warehouse. |
| K [ Back to top ] |
| Key |
A
database "Key " is an attribute used to sort
and/or identify data contained in a table. Each table has
a primary key which uniquely identifies records. Foriegn
keys are utilized to cross-reference data between relational
tables. |
| L [ Back to top ] |
| Local
Access Database (LAD) |
A
database that serves individual systems and workgroups
as the end point for shared data distribution. LADs are
the retail outlets of the data warehouse network. They
provide direct access to the data requested by specific
systems or desktop query services. |
| Logical
Data Model |
Actual
implementation of a conceptual module in a database.
It may take multiple logical data models to implement
one conceptual data model. |
| M [ Back to top ] |
| Mainframe |
A
term originally referring to the cabinet containing the
central processor unit or "main frame" of a
room-filling “batch” processing machine. After
the emergence of smaller "minicomputer" designs
in the early 1970s, the traditional “big iron” machines
were described as "mainframe computers" and
eventually just as mainframes. |
| Many-to-Many
(M:M) |
A
many-to-many relationship signifies that many instances
of a given entity relate to many instances of another entity. |
| Master
Table |
The
relationship between tables is like a ‘master and slave’ relationship.
The master controls the detail. |
| Metadata |
Data
that describes the data in a database. It
includes the names of tables, columns and indexes, how
the data items are used, business definitions, relationships
between data, how the data has been processed and information
about how current the data is. |
| Multi-dimensional
Database (MDBS and MDBMS or MDDs) |
A
powerful database that lets users analyse large amounts
of data. An MDBS captures and presents data as arrays
that can be arranged in multiple dimensions. |
Multiple
table queries |
Multiple
table queries are queries that use more than one table. |
| N [ Back to top ] |
| Normalistion |
In
relational database design, the process of Normalisation
is organising table data
to minimise
duplication.
"Normalisation
involves dividing a database into 2 or
more tables and defining relationships between the
tables. The objective of
normalisation is
to isolate data so that additions, deletions and modifications
of data fields can
be made in just one table and then propagated (spread) through
the rest of the database using
pre-defined
relationships”
|
| Normal
Form |
A
Relational Database can provide control over how data
is used and how the data is stored and shared with
other users. The database stores information in a series
of linked tables, designed in a way that minimises
the number of repeating data items. Such systems provide
facilities that make it easy to index and manage large
amounts of data in many tables thereby permitting efficient
data storage.
Normal Forms are the series of
logical steps applied to database data and tables
|
| Navigation
Bar |
In
FrontPage, a collection of graphical or textual buttons
containing hyperlinks to pages that are part of the same
web structure |
| Network
Model |
The
objective of a network model is to separate data structure
from physical storage, eliminate unnecessary duplication
of data with associated errors and costs. It uses the
concept of M:N linkages or relationships |
| O [ Back to top ] |
| One-to-One
(1:1) |
A
one-to-one relationship signifies that each instance of
a given entity relates to exactly one instance of another
entity. |
| One-to-Many
(1:M) |
A
one-to-many relationship signifies that each instance of
a given entity relates to one or more instances of another
entity. |
| P [ Back to top ] |
| Picture |
A graphics file that can be inserted
on a Web page and displayed in a Web browser. FrontPage for
example lets you import graphics in the following
formats: GIF, JPEG (standard and progressive), BMP
(Windows and OS/2), TIFF, TGA, RAS, EPS, PCX, WMF,
and PNG. Imported graphics are converted to GIF format
(for graphics containing up to 256 colors) or JPEG
format (for graphics containing over 256 colors) when
the page is saved to the current web. Also called image. |
| PL/SQL |
Was
introduced, as a procedural extension to SQL by the Oracle
Corporation with the release of Oracle 6. Its main functions
were to allow for the provision of a procedural language
available to Oracle programs without the need to pass
control back to the user after the execution of every
SQL statement (one of the weaknesses of SQL being that
the user can only execute a single statement at one time) |
| Plug
In |
One
of a set of software modules that integrate into Web
browsers to offer a range of interactive and multimedia
capabilities |
| Primary
Key |
Unique
Identifier for the
primary COLUMN in
the table -
and the data item that uniquely identifies each record.
• Use integers
to save memory & increase
speed
• Can
be “composite” or “compound” Key
(means
made of multiple parts [or multiple keys])
|
| Q [ Back to top ] |
| R [ Back to top ] |
| Referential
Integrity |
Referential
Integrity is a feature provided by Relational
Database Management System (RDBMS) that
prevents users or applications from entering inconsistent
data. Most RDBMS have various referential integrity
rules that are automatically applied when you create
a relationship between two tables. |
| Relational |
Therefore
relational database systems can use multiple tables to
store information, and each table can have a different
record format |
| Relationship |
The
various relationships both between the data items forming
the various entities and the relationship between entities
themselves. |
| Rollback & Commit |
A
standard mechanism for ensuring completion of a set of
transactions involves; commit (like a Save) and rollback (rolls
the data back to the previous, ‘good’ save). |
| S [ Back to top ] |
| Script |
A
type of computer code that can be directly executed by
a program that understands the language in which the
script is written. Scripts do not need to be compiled
to be run. |
| Second
Normal Form |
A record is in Second Normal Form provided it
satisfies the condition for 1NF and also all non-key
data items are fully functionally dependant on the primary
key. |
| Server |
A
computer that offers services on a network. On the World
Wide Web, a server is a computer that runs the Web server
software that responds to HTTP protocol requests. Also
called host. |
| SQL |
Structured
Query Language - is a standard relational database language,
it is used by the majority of systems now to retrieve
and update data held on a database. |
| T [ Back to top ] |
| Third
Normal Form |
A
record is in Third Normal Form provided it satisfies
the condition for 2NF and also no non-key data item is
functionally dependant on any other non-key data item. |
| Type |
this
is a set of pre-defined characteristics, which control
the behaviour of data. Database data of type ‘currency’ will have a currency symbol prefix £ or $ and can
only be in a numeric format. Attempting to enter a letter
in a database field of type currency will generate an
validation error. |
| U [ Back to top ] |
| Uniform
Resource Locator (URL) |
is
a fancy name for address. The
URL contains information about where the file is to
be found and what actions a browser should take with
the file.
URL’s
can be either ‘relative’ or ‘absolute’.
Relative
addressing means the file can be found locally within
a web site or hard disk drive e.g. normalise/1nf.htm
- 1nf.htm can be found within the folder called normalise.
Absolute
web addressing means the address is global, that is it has;
http:// www.norm.com before
the norm/1nf.htm – think of an absolute address; like
a postal address, without all the parts of the address, mail
cannot be delivered to the correct destination. |
| V [ Back to top ] |
| Validation |
a
name for the method of ensuring data is entered in
the correct format, length or case.
If
a validation
rule for a database field is contravened, then
an error message should be displayed.
|
| Verification |
in
a database; verification
rules are used to intercept typographic errors or
spelling errors. |
| W [ Back to top ] |
| W3C |
is
short for World Wide Web Consortium. The Consortium www.w3c.org is
solely concerned with web universality. It promotes
the use of common formats, increasing browser compatibility
and encourages web designers to adhere to a series
of standards. Their aim is to improve the web for all.
(Try ‘file/view
source’ on this page; to see the HTML source code;
look at the top for W3C references!)
|
| World
Wide Web |
technically
a sub-set of the Internet – the
web comprises of a series of hyperlinked files and documents,
stored on servers. Commonly used to describe any computer
resource, that can be reached or accessed using a web
browser. |
| X [ Back to top ] |
| XML |
Extensible
Markup Language: an newer improved, but more complex
version of HTML.
Its
purpose is to disentangle all the HTML tags and formatting
commands from within web pages.
This
will allow – in the future – significant improvements
in Internet search engine performance, because all
the formatting commands will be ‘tagged’ as ‘code’ and
thus ignored in web searches.
|
| Y [ Back to top ] |
| Z [
Back to top ] |
