Furthermore, the volume/size of a database can differ extensively from a few megabytes for personal databases to huge terabytes of large business databases. The data and information of a business or personal database is stored on a nonvolatile medium that can hold huge amounts of data. However, the most frequently utilized storage mediums are magnetic disks. Magnetic disks are capable to store huge amount of data as compared to computer memory, at a great deal lower cost per unit of data. For data organization, logically data in RDBMS are structured like a group of relations/tables, each table/relation composed of a group of records (Hoffer, Prescot, & Topi, 2009; Shelly, Cashman, & Vermaat, 2005).
DDC (Data Definition Command) is utilized to describe the database as well as other linked functions similar to creating views, tables, indexes etc. Below I will outline some data definition commands (Hoffer, Prescot, & Topi, 2009):
Data control commands in SQL allow us to control access to data inside the database. These data control commands are usually employed to create objects and to control the allocation of privileges among users. A number of data control commands are (Hoffer, Prescot, & Topi, 2009):
A View contains a stored query which is accessible like a virtual table composed of resultant group of a query. As compared to ordinary tables in a RDBMS a view is not a structured part of the physical representation. It is a dynamic, virtual table calculated or gathered from data in the database. Altering the data in a table changes the data represented in subsequent invocations of the view. Security in views can be applied for the users as the underlying tables are not straightly accessible. Thus, it helps DBA present users simply the data they require, as protecting additional data in the same table (Hoffer, Prescot, & Topi, 2009).
To create a view