O

Object:

An object in object methodology is the iteration of a class at run-time, such that multiple object instances can be created from a class. And object is also a generic term applied to anything tangible , such as a table in a relational database.

Object Database Model:

An object database model provides a three-dimensional structure to data where any item in a database can be retrieved from any point very rapidly . Whereas the relational database model lends itself to retrieval of groups of records in two dimensions, the object database model is very efficient for finding unique items. Consequently the object database model performs very poorly when retrieving more than a single item, which the relational database model is very good at.

Object-Relational Database Model:

The object database model is somewhat spherical in nature, allowing access to unique elements anywhere within a database structure, with extremely high performance. The object database model performs extremely poorly when retrieving more than a single data item. The relational database model, on the other hand, contains records of data in tables across two dimensions. The relational database model is best suited for retrieval of groups of data, but can also be used to access unique data items fairly efficiently . The object-relational database model was created in answer to conflicting capabilities of relational and object database models and also as a commercial competitor to the object database model.

OLTP:

See Online Transaction Processing .

OLTP Database:

See Online Transaction Processing .

Online Transaction Processing:

OLTP databases were devised to cater to the enormous concurrency requirements of Internet (online) applications. OLTP databases cause problems with concurrency. The number of users that can be reached over the Internet is an unimaginable order of magnitude larger than that of an in-house company client-server database. Thus, the concurrency requirements for OLTP database models explode well beyond the scope of previous experience with a client-server database.

Open Source:

A term applied to software that is free to use, but often more complex and less reliable to develop with. MySQL and Postgres are open source databases.

Open Standard:

A standard applying to open source software (see Open Source ).

Operating System:

The lowest level of software on a computer, generally managing the interface and the hardware. Windows, UNIX, and Linux are all operating systems.

Operations:

A term applied to the operations of a company. What does a company do to make a profit?

Operator:

In programming terms an operator is a special type of operation operating on two separate expressions. For example, in the expression (p AND q) , AND operates on both p and q, requiring that both are true to return a true result to the expression of both p and q at the same time. Also, in the expression (3+4) the plus sign is the operator that adds together the values 3 and 4.

ORDER BY Clause:

Query SELECT command adjustment allowing re-sorting ( reordering ) of records as they are returned from a query to a database.

Outer Join:

An outer join finds the intersection of two tables using an SQL join query, plus rows in one table and not the other. The result depends on whether the outer join is a left outer join, a right outer join, or a full outer join.