-Designing -Implementing -Testing

5.Design and development of database.

The database concept has evolved since the 1960s to ease increasing difficulties in designing and maintaining complex information systems (typically with many current end-users, and with a large amount of diverse data)

Database design is the process of producing a detailed data model of database. This data model contains all the needed logical and physical design choices and physical storage parameters needed to generate a design in a data definition language, which can then be used to create a database. A fully attributed data model contains detailed attributes for each entity.

The term database design can be used to describe many different parts of the design of an overall database system. Principally, and most correctly, it can be thought of as the logical design of the base data structures used to store the data. In the relational model these are the tables and views. In an object database the entities and relationships map directly to object classes and named relationships. However, the term database design could also be used to apply to the overall process of designing, not just the base data structures, but also the forms and queries used as part of the overall database application within the database management system (DBMS).

The process of doing database design generally consists of a number of steps which will be carried out by the database designer. Usually, the designer must:

• Determine the data to be stored in the database.

• Determine the relationships between the different data elements.

• Superimpose a logical structure upon the data on the basis of these relationships.

Within the relational model the final step above can generally be broken down into two further steps, that of determining the grouping of information within the system, generally determining what are the basic objects about which information is being stored, and then determining the relationships between these groups of information, or objects.

6. Specify local and wide area networks.

A computer network is a telecommunication network which allows nodes to share resources. Networking is an important aspect of the modern computer environment, allowing people and companies to communicate and share resources quickly. Connected groups of computer are called networks and there are usually either local area networks (LAN) and wide area network (WAN). Local area network a network that connects a relatively small number of machines in a relatively close geographical area.

Various configurations, called topologies, have been used to administer LANs.

• Ring topology A configuration that connects all nodes in a closed loop on which messages travel in one direction

• Star topology A configuration that centers around one node to which all others are connected and through which all messages are sent

• Bus topology All nodes are connected to a single communication line that carries messages in both directions

Often one particular not on a LAN is set up to serve as a gateway to handle all communication going between that LAN and other networks.

A wide area networks(WAN) is a telecommunications network or computer network that extends over a large geographical distance.

A WAN is far more geographically dispersed network than a LAN. A WAN can be one large network or a number of linked LANs. Computers connected to a WAN are through public networks such as the telephone systems with LANs.