Mapping is a process of converting on level to another level. There are two levels of mapping: • From the conceptual level to the internal level • From the external level to the conceptual level Conceptual / Internal Mapping: The conceptual/internal mapping defines the association between the abstract view and stored database. It specifies how conceptual records and fields are represented... 

Database can he viewed at three levels. The levels form three-level architecture and are depicted by three models. The models refer to the permanent structure of the database, not to the data that is stored at any given moment. A database model is a collection of tools. It may include a type of diagram and specialized vocabulary for describing the structure of the database. The purpose of the three-level... 

Dr. E. F. Codd worked to improve the working of DBMSs for handling large volumes of data. He applied the rules of mathematics for solving the problems of earlier database models. Some important problems were: • Data integrity • Data redundancy Dr. Codd presented a paper “A Relational Model of Data for Large Shared Databanks” in June I 970 that contained 12 rules. A DBMS that satisfies these... 

To overcome the problems of the hierarchical data model, the Network Model was developed. The network model modified the hierarchical model by allowing multiple parent-child relationships. These relationships are known as sets in a network model. The network model structures and language constructs were defined by the CODASYL (Conference on Data Systems Language). The Network Model 1. Characteristics... 

One of the earliest database management systems was based on the hierarchical model. In a hierarchical data model, the records have a parent-child relationship. Consider the application used for Production Planning in automobile manufacturing companies. The model of the database is shown in the following figure. The automobile manufacturer manufactures various models of cars. Each car model is decomposed... 

Another way to design an information system is known as staged database design approach. It is a top-down approach. It begins by analyzing the general requirements of the organization: As the process continues, these problems are analyzed in more details. The steps in this approach are as follows: Analyze User Environment: The first step in designing a database is to understand and analyze the... 

System development life cycle (SDLC) is a conventional way for developing an. information system. It consists of many steps and involves different persons. Different step of SDLC are as follows: Phases of System Development Life Cycle Preliminary Investigation: Preliminary investigation is the first phase of System Development Life Cycle. The main objective of this phase is to identify deficiencies... 

The development of a complete database application is a lengthy and complicated process. Different strategies can be used to develop database applications. Following is a brief discussion about different strategies and steps performed during this process: General Strategies: A database application is developed to satisfy the requirements of the user. It is very important to understand these requirements... 

There are different types of user that play different roles in a database environment. Following is a brief description of these users: (1) Application Programmers: Application programmer is the person who is responsible for implementing the required functionality of database for the end user. Application programmer works according to the specification provided by the system analyst. (2) End Users: ... 

The range of database application is as follows: (1) Personal Computer Database: Personal computer databases are specially designed for single user. The user may be using stand-alone desktop computer or laptop. The representatives of a medical company may use laptop computers when working in the market. This computer may use a simple database application in which the records of customers are stored....