Types of database structure

A database is a collection of data
o Maybe computerized
o Will be organized so as to make the retrieval and maintenance of data as easy as possible

Two types of database structure. Databases typically have one of two basic forms:
*Single-file or flat file database
*Multi-file relational or structured database

Flat file
A flat file is a database held in a single file. The data stored in one file cannot easily be linked to data stored in another file. A flat file, also known as a text database, is a type of database that stores data in a plain text format. Flat files typically text files that have all word processing and structure markup removed. A flat file features a table with a single record per line.

They are only suitable for very simple databases. The patient database is an example of a flat-file as all of the information is stored in one single table.

Multi-file relational
A database that is perceived by the user as a collection of two-dimensional tables. A relational database contains multiple tables of data that relate to each other and allows the user to specify information about multiple tables and the relationships between those tables, allowing more flexibility and control over database constraints. This database management system has the capability to recombine data elements to form different relations resulting in a great flexibility of data usage.
Types of database structure

Structure of operating system

Operating system performs three functions:
*Convenience: An OS makes a computer more convenient to use.
*Efficiency: An OS allows the computer system resources to be used in an efficient manner.
*Ability to evolve: An OS should be constructed in such a way as to permit an efective development, testing and introduction of new system functions without at the same time interfering with service.

Every operating system has its own internal structure in terms of file arrangement, memory management, storage management, etc, and the entire performance of the system depends on its structure.

The elementary approach to structure an operating system is simple structure. Simple structure OS systems are small, simple and limited systems. MS-DOS is an operating system designed with this approach.

Structure of MS-DOS

An operating system may process its workload serially or concurrently. That is resources of the computer system nay be dedicated to a single program until its completion, or they may be dynamically reassigned among a collection of active programs in different stages of execution.

The main element of an OS that a user sees is the graphical user interface or GUI. This is the display and the method of interaction that the user can take to manipulate the OS via the display.

For example, in a personal computer OS such as Windows 7, the user can see a desktop, a background and icons. These are manipulated by way of the keyboard and mouse usually. In a mobile computer OS such as Android, the user can see a main screen with icons that can be manipulated with his fingers, with stylus or by voice.
Structure of operating system