Changes

The most commonly used organization is ''relational'', in which the data in the [[database table|table]]s are organized as rows (records) and columns (fields).  Relational databases differ from other database organizations in that each row has the exact same fields as every other row for a given table, although some fields may be unused for some rows.  Keys are defined as being one or more columns and data lookups using keys is much faster than lookups based on non-key fields.  Fields in one table can be associated with related fields in other tables, hence the name "relational", and data can be looked up by simple <i>join</i> operations that returns records from several tables based on these related fields.

The most commonly used organization is ''relational'', in which the data in the [[database table|table]]s are organized as rows (records) and columns (fields).  Relational databases differ from other database organizations in that each row has the exact same fields as every other row for a given table, although some fields may be unused for some rows.  Keys are defined as being one or more columns and data lookups using keys is much faster than lookups based on non-key fields.  Fields in one table can be associated with related fields in other tables, hence the name "relational", and data can be looked up by simple <i>join</i> operations that returns records from several tables based on these related fields.

''Relational databases'' have become popular due to high speed.   

[[Relational database]]s have become popular due to high speed.   

SQL created by EF Codd at IBM (see his paper the relational model) is [[Structured Query Language]], a language for manipulating large data tables within a database.  Most relational databases support the use of SQL.  Users ask for the data they write a "[[database query|query]]" using SQL and the database quickly returns the data.

SQL created by EF Codd at IBM (see his paper the relational model) is [[Structured Query Language]], a language for manipulating large data tables within a database.  Most relational databases support the use of SQL.  Users ask for the data they write a "[[database query|query]]" using SQL and the database quickly returns the data.

== Available Databases ==

== Available Databases ==

There are some big database vendors in the software business such as Oracle, IBM's DB2, SAP, SYBASE, Microsoft SQL Server, Versant as well as some free software alternatives such as postgresql, firebird, and MySQL.

There are some big database vendors in the software business such as Oracle, IBM's DB2, SAP, SYBASE, Microsoft SQL Server, Versant as well as some free software alternatives such as postgresql, firebird, and MySQL.

[[Category:Software]]

[[Category:Software]]