Information Modeling By means of Entity Relationship (ER) Method Part – 7

Identifying Information Objects

The names must have the subsequent properties:

· Exclusive

· Having a sense to the end user

· Enclosing the least total words which are desirable to exclusively as well as to exactly define the object.

For entities as well as columns or attributes, names are particularly nouns while on other hand the relations name is usually verbs.

A number of specialists recommend not using acronyms or short form for the reason that they may lead to misperception about what it really signifies. Other have confidence in using acronyms or short form because it have a satisfaction delivered to the users for the reason that they are commonly castoff as well as understood inside the organization.

An individual must take care of the classification as well as resolve any alternative word for the entities and columns or attributes. This can occur in big projects where various branches make use of dissimilar terms for the similar type of object.

Object Description

Comprehensive as well as precise descriptions are significant for making sure that every database system users who are involved in the modeling of the information know accurately what notions the objects are demonstrating.

Descriptions must practice terms which are acquainted to the database system user as well as should precisely elucidate what the object is signifying as well as what part it has in the enterprise. A number of specialists suggest end users to offer the descriptions. When abbreviations, or else the terms which are used in the description are not commonly understood, then these abbreviations or else the terms must be redefined.

At the time of describing the objects, the designer must be cautious enough to solve whichever occurrences where a solo entity is in point of fact demonstrating two (2) dissimilar notions (Homonyms) or else where two (2) dissimilar entities are in point of fact demonstrating the identical "item" (Synonyms). This circumstance usually rises for the reason that persons or organizations may possibly ponder about an occurrence otherwise procedure in terms of their specific purpose.

An instance of a Homonym can be a circumstance where the Advertising department describes the entity MARKETPLACE in terms of topographical areas while on the other hand the Sales departments considers this same entity in terms of demographics. Without solving, the outcome will be an entity with two (2) dissimilar senses as well as properties.

On the other hand, an instance of a Synonym can be the Amenity department where they have recognized an entity known as CUSTOMER while on the other hand Assistance Desk has recognized the same entity as CONTACT. In actuality, they may have possibly meant the similar thing, an individual who associates or else calls the organization for help when they have any sort of problems. The purpose of synonyms is significant with the intention of dodging the repetitions as well as to evade any likely reliability or else the integrity difficulties.

Recording Facts in Design Document

The design document accounts the complete facts about every single object castoff in the model. As an individual label, describe, as well as define objects, this facts must be retained in this document. If an individual are not making use of an automatic designing tool, then the documentation can be prepared on plain paper or else with a word processor (for an instance the Microsoft Word). There is no benchmark for the business of this document however the documentation must consist of facts about labels, descriptions, as well as definition for columns or attributes, and domains.

Two (2) documents which are the ENTITY – ENTITY (E & E) matrix and the ENTITY – ATTRIBUTE (E & A) or ENTITY – COLUMN (E & C) matrix castoff in the modeling method are beneficial for keeping track of the objects.

The ENTITY – ENTITY (E & E) matrix is a two (2) dimensional array for specifying associations among the different entities. The labels of every recognized entity are recorded along both axes. As associations are first (1^st) acknowledged, an "X" is positioned in the interconnecting points where any of the two (2) axes join to specify a conceivable associations among the objects involved. As the association is more categorized, the "X" is substituted using the symbolization specifying cardinality.

The ENTITY – ATTRIBUTE (E & A) or ENTITY – COLUMN (E & C) matrix is castoff to designate the task of attributes o columns to entities. It is alike in form to the ENTITY – ENTITY (E & E) matrix except for attribute or column names are recorded on the rows or tuples.

The below illustration displays an instance of ENTITY – ENTITY (E & E) matrix and the ENTITY – ATTRIBUTE (E & A) or ENTITY – COLUMN (E & C) matrix.

In the upcoming part we will be discussing how to Creating the Simple Scheme, Binary Relationships, One to One (1 to 1), One to Many (1 to N), Many to Many (N to N), and Recursive Relations.