D

Data:

A term applied to organized information.

Data Centric:

A data-centric XML document in its purest form uses XML data as a method of transporting data between computers. In reality, XML is often a mixture of data-centric and document-centric data. Data-centric XML is generic and program accessible because it is repetitive.

Data Integrity:

The processes and mechanisms where data is maintained in a sensible and usable state. In other words, child records are deleted before parent records. Also, changes made to parent records, affecting child records can sometimes be propagated into child records.

Data Warehouse:

A large transactional history database used for predictive and planning reporting.

Database:

A database is a collection of information, preferably related information, and preferably organized.

Database Model:

A model used to organize and apply structure to otherwise disorganized information.

Database Procedure:

See Stored Procedure .

Data Type:

A simple data type restricts values in fields, such as allowing only a date or a number. More complex data types can comprise a composite of many simple data types, or even binary objects containing multimedia, and otherwise.

Date Data Type:

A special data type for storing dates and times.

Decimal:

Decimal data types contain decimal numbers , usually with fixed position decimal points.

Default:

A setting used as an optional value for a field in a record when a value is not specified.

DELETE:

An SQL command used to destroy records in relational tables.

Demographics:

The science of breaking a population into groups, which can provide useful analytical results. Demographics is the study, characteristics, and distribution of human populations. Distribution can be according to whatever criteria are specified. For example, population can be described through (divided up by) language distribution, occupation distribution, infant mortality rates, economics, and so on. Demographics is a science applying to subject areas such as geography, marketing, consumer activities, medicine. Essentially anything, depending on what questions are asked of a population.

Denormalization:

Denormalization is most often the opposite of normalization, more commonly used in data warehouse or reporting environments. Denormalization decreases granularity by reversing normalization, and otherwise.

Descendant:

Any node that is a child, grandchild, and so on of the current node.

Descendant Node:

See Descendant .

Descending Index:

An index that is built sorted in descending order, such as C, B, A.

DHTML:

See Dynamic Hypertext Markup Language .

DNS:

Directory names service, converting names such as yahoo.com to an IP address.

Document:

See XML Document .

Document-Centric:

A document-centric XML document suitable for human consumption is essentially not really easily understandable by a computer, if at all possible. Document-centric XML is essentially the type of documents that would normally be written by hand, by an author, such as a Word document, a PDF document, or even something like this book.

Document Type Definition:

The DTD allows the definition for the building blocks of an XML document. In other words, you create a DTD document. That DTD document contains the structural definition for the data in an XML document. That DTD definition can be used as a mapping structure, mapping between the metadata, plus data mix in an XML document, and the metadata table structure of a relational database model.

DOM:

See Document Object Model .

DROP INDEX:

A command used to drop an index in a relational database.

DROP TABLE:

A command used to drop a table in a relational database.

DTD:

See Document Type Definition .

Dynamic:

In computer jargon this term is used to describe something that changes frequently, or something that can be created depending on the current state of data in a database.

Dynamic Data:

Data that changes significantly over a short period of time.

Dynamic HTML:

See Dynamic Hypertext Markup Language .

Dynamic Hypertext Markup Language:

The dynamic of HTML where HTML, CSS, and scripting languages such as JavaScript are combined. All these things are combined to create HTML pages that can change dynamically in real time.

Document Object Model:

All browser languages such as HTML and XML are interpreted when loaded into a browser. In other words, there is a program in the browser (its called a parser) that not only validates web page content, but also executes any commands contained in those pages. The DOM is the structure of something such as an HTML or XML document, which the browser interpreter uses to parse those web pages.