Data Processing Cycle
Before we discuss the database, it shall be better if we discuss the data processing cycle in the context of accounting. Data processing involves collection, sorting, relating, interpreting and processing in such a manner that raw data provides meaningful information. The quality of information is directly related to the data used. Therefore, it is important that quality, with respect to the steps involved in data processing cycle, which are data capturing, data input, processing and generating information available to the user, is ensured.
Model of Database for Accounting
An organization is established to undertake one or several operations or projects. Typically, it is an environment with a single administrative control. Examples of organizations are banks, hospitals, manufacturers, etc. All these organizations have different functions, but still there are some basic or common functions performed by all the organizations. One common function for all the organizations is accounting.
Entity - Relationship (ER) Model
The entity - relationship (ER) data model is developed out of the exercise of using commercially available DBMS to model application database. Earlier, commercial systems were based on the hierarchical and network approach. The entity - relationship model is a generalization of these models. It allows the representation of explicit constraints as well as relationships.
Entities are the basic units used in modeling classes of concrete or abstract objects. An entity is an object that is of interest to an organization. Objects of similar types are characterized by the same set of attributes or properties. In other words, we can say that the independent existence of a thing is known as entity. Two objects are mutually distinguishable and this fact is represented in the entity set by giving them unique identifiers.
Attributes and Identifiers
The properties that characterize or further describe an entity are called its attributes. Each object must be separately identified as an entity. Identifying and classifying the objects into an entity can be difficult, because an object can belong to different entities at the same time or two or more entities may be similar. In such cases, they need to be further described so that each entity is distinguished and separately identified. Entities are distinguished and modeled using their characteristics or attributes. An association exists between different attributes of an entity. An association between two attributes indicates that the values of the associated attributes are interdependent.
An association among entities is called a relationship. The relationship set is used in data modeling to represent an association between entity sets. This association may have certain properties represented by the attributes of the relationship set. A collection of relationships of the same type is called a relationship set. A relationship that involves N entities is called N - ary relationship.
Weak Entity Type
A weak entity is one which does not have an identifier of its own. A weak entity type is identified with respect to its relationship because it cannot be identified without its owner entity. Let us consider a voucher. A voucher may be accompanied by a set of support documents, such as bills, detail of expenses, issued by other parties to the transaction. Such support documents are weak entity type which are used to keep track of support documents attached to each voucher via N- relationship.
Database technology refers to a set of techniques used for designing a database. Database design requires use of several techniques of certain concepts at the same time. These concepts consist of reality, data, database, information, DBMS and database system.
Database Management System (DBMS): DBMS is a collection of programs that help us to create and maintain a database. It is a general purpose software system that facilitates the processes of defining, constructing and manipulating databases for various applications. The data stored need not include every conceivable piece of fact about the enterprise. Usually, only the facts relevant to an enterprise are captured and organized.
Relational Data Model
The Relational Data Model, after more than a decade, has emerged as a commercial product from the research, development, test and trial stages. It represents the database as a collection of relations, which resembles a table of values. Each row of the table represents a collection of related data values. The table name and column names are used to help in interpreting the meaning of values in each row. Each row of a table is called a data record.
Relational Databases and Schemas
A Relational Database Schema is made up of a number of relational database schemas and also a set of integrity constraints. A relational database is based ion relation scheme consisting of a number of attributes. It is a set of relation states such that every relational database state satisfies the integrity constraints specified on relational database schema. From another point of view, a relation is a subset of the Cartesian product of the domains.