Database management system |Relational Data Model Concepts
7.1 Relational Data Structure In relational data model, a database is represented as a collection of relations. A relation can be considered as a table of values. Each row in a table corresponds to a real world entity or a relationship. A relation has;
Database Management Systems|Data Modeling using the Entity Relationship Model
5.1 Stages of Database Development As in any other development process, the database design also involves a number of stages carries out at different contexts. How ever, initially the UoD needs to be identified and studied before moving on to other stages. The figure 5.1 will illustrate the stages in database development, and then we will take the important ones for the discussion.
Database Management Systems|Database System Architectures
4.1 Centralized Database Systems The centralized database systems run on a single computer system. It can either be a single user database system which runs on a personal computer, or else a database system which runs on a high performance computer such as a mainframe, which will be accessed through dumb terminals. The dumb terminals will only user for data input and output.
Database Management Systems| Data Model and Three-Schema Architecture
3.1 Data Model By definition, a database is a collection of interrelated data, which represents some Universe of Discourse (UoD). Based on the UoD concerned, the database and the data stored in the database might vary. Thus it pops up the requirement of a structure for the database into which the actual data would be saved and from which the required data are retrieved. The data model is considered to be the collection of concepts which describes the structure of the database. The database and the structure represent the UoD.
Database Management Systems
Database Types 2.1 Types of Databases The databases can be categorised based in various perspectives. One such way is to consider with the scope and the applicability of the database. Following will help you to identify the basic features of each Database type categorised based on the scope and applicability.
Database Management Systems
1.1 Data,Information and Universe of Discourse Have you ever noticed that people often say “I don’t have enough information” than saying “I don’t have enough data”. Can you justify this difference? Why people look for information rather than for data? Data are the known facts that can be recorded. They have an implicit meaning. That is data will rather have a meaning which is embedded or inherent to it. The meaning contained in data will help to infer additional facts or information.In the contrary, information is processed data which is presented in a form suitable for human interpretation and have an explicit meaning. Information helps to reveal trends or patterns and therefore supports decision making.
1. Introduction The term reasoning can be understood in many ways: drawing conclusions, solving problems, making inferences, etc. Obviously, there are many approaches to drawing conclusions or making inferences. Some of the reasoning approaches may not provide strong or valid conclusions all the time. For example, scientific reasoning appears to be strong but it can be falsified with the emergence of new scientific theories. In contrast, mathematical reasoning always preserves the truth. There are several other approaches to reasoning. This article discusses various approaches to reasoning with a particular emphasis on what is called deductive reasoning. This is because; of the concept of Logic Programming.