Structure Query Language. Relational database programs, such as Oracle or MySQL, recognize this language. A user can write SQL scripts that create databases and tables, insert data into databases, and draw that data back out. Each database program utilizes a different version of SQL, but most are very similar, so once you learn SQL on one database, it is not difficult to use it on others.

There are 2 types of database:

Flat File: Everything is stored in one big table - like a telephone directory or a spreadsheet.
Relational: Similar data is grouped together into separate tables, for example, a Library Database may have:

• a table storing Customers Details
• a table storing Book Categories
• a table storing Book Details
• a table storing Lending Records

The tables are related together using a unique identifier for each record.

• BookID (unique field)
• BookName text field

A relational database minimizes data errors, redundancy and duplication since each record needs to be stored only once. It also promotes data integrity/accuracy which means data storage costs are minimized.