Literature Review: Each student is required to write a 10-15 page literature review on a topic related to the course content. It is important to remember that there is a significant difference between...

Entity Relationship Model- Notations
Literature Review
Abstract
This paper focuses on reviewing the literature on the fundamental concept of Entity Relationship Model (ERM) and the notations that are widely used for the development of an ERM along with a comparison among them to illustrate each of their uniqueness. The components that are used to model the logical view of a system from data perspective are discussed in general, as they form the basic foundation of a database development. The different notations used in developing an entity relationship diagram and how their features differ from each other, are discussed on the basis of available literature. The review concludes by deducing which form of notation proves to be the best for teaching purposes as well as organizational purposes in order to attain best results in terms of user’s understanding.
Contents
Abstract    2
Introduction    4
Literature Review    5
ERM Basic Components    6
Entity    6
Relationship    6
Attribute    7
Cardinality    7
Participation    7
Specialization    8
ERD Notations    8
Chen Notation    9
Teorey’s Notation    9
Elmasri and Navathe    9
Korth and Silberschatz    10
McFadden & Hoffer    10
Batini, Ceri and Navathe    10
Oracle Case Method    11
Information Engineering Notation    11
Information Model Notation    12
Bachman Notation    12
Conclusion    13
Bibliography    15
Introduction
The purpose of this article is to review the literature on different notations that are used in the development of entity relationship diagram. Entity Relationship Modelling is the building block for a database design and is crucial to Information System Modelling (Badia, 2004). As states in historical events, ERM played an important role in defining the Computer aided Software Engineering (CASE) Tools through the symposium in Atlanta as mentioned in (Chen P. P.) The review illustrates the basic concept of ERM where basic components like entity, relationship, attribute, cardinality, participation and specialization/generalization are elaborated. An ERD would be incomplete without the discussion on any of the mentioned components. These features are further incorporated into databases with the help of notations. On the basis of these notations, data models can show similarities among various devices, set standards for updating and finding the required information and lastly, recognizing the errors or discrepancies (T. R. G. Green, 1995) in the conceptual model and the actual implementation design of a database. The notations help the modeler and developer to display the information for better analysis. The complexity of relationships and the cardinality among them can be represented clearly through the notations. As stated in (Eid, 2012), ERM with appropriate notations can prove to be a useful tool in depicting the effectiveness of a system and utility of the database. It would inspire the user to understand the scenario better to build the database according to the system requirements along with depicting it correctly. Various types of notations have been offered by different authors which may or may not discuss each component explicitly but cover the requirement of any scenario on the basis of their advantages. The notations may be semantically equivalent (Helen C Purchase, 2004) but their selection may not be based on the ease of the user’s understanding. The various notations discussed in this literature review consider common factors for comparison on the basis of which the best suitable notation type is suggested for the students and the organizations to use according to their requirement (Chen P. P.-S., 2005).
Further to the discussion on basic components of the database, the paper outlines the characteristics considered for discussing the various types of notations. Following those, the notations that are discussed in detail are Chen notation, Teorey’s Notation, Elmasri and Navathe, Korth and Silberschatz, McFadden & Hoffer, Batini, Ceri and Navathe, Oracle Case Method, Information Engineering Notation, Information Model Notation, Bachman Notation.
Keywords (20-25): Entity-Relationship Model (ERM), Entity-Relationship Diagram (ERD), notation, modeling, constraints, database, method, binary model, n-ary model, entity, attributes, participation, cardinality, relationship, disjoint subclasses, overlapping.
Literature Review
The basic concept of developing an ERM evolved due to the need of outlining the structure of a database and the constraints associated with it. An ERM is a conceptual data model of database applications which is employed by numerous designing tools (Ramez Elmasri, 2009). The author states that the methodologies used in developing ERM delve into the database design to specify the modules and how they interact among themselves using various diagrams. An ER Diagram is a diagrammatic representation of the concept of a business scenario. The diagrams, commonly known as entity-relationship diagram are similar to class diagrams. As explained in (Ling, 2015), ERD helps the user to preserve the semantics of real world over the target scenario and it allows data independence thus facilitating a better logical design.
ERM Basic Components
This section first explains the basic components that are used to conceptualize an ERM as described by Chen in 1976 and further compares the notations that are conveniently used now a days as described in (Yeol Song, 1995). Chen focused on entities and relationships and introduced diagrammatic representation for database design which were inspired by Bachman diagrams. The strengths and weakness of ERM may be understood by observing its internal structure which is composed of basic elements discussed below. Considering the limited ease of its usage (Badia, 2004), an ERD can demonstrate enough semantics to produce a clearly understandable design in congruence with the database requirements.
(Yeol Song, 1995), (Chen, 1976) and (Stanley Phillip) discuss the basic features of an ERM as follows:
Entity
Entity is a real-world object which independently exists as a concept or physically. It is an important thing that may have more than one features associated with it. Entity which has no feature of its own and whose existence may depend on another entity is a weak entity and entity with its own different features is a strong entity. For example, a simple database of StoreEnterprise may contain several entities like Employee, Store, department, etc. The first two are strong entities. A department can exist only if a store is present for that department, thus making it a weak entity, dependent on Store.
Relationship
Relationship is an association with two entities. An instance of a relation contains one entity from each entity type (Ramez Elmasri, 2009). Relationships can be binary, ternary or n-ary. However, they are converted to binary in order to simplify the ERM. This also reduces redundancy of data storage at the machine level. As the authors state in (Yeol Song, 1995), an example of student database, the entities Student and Book may be related through Borrow relationship. (Trevor H. Jones, 1996) describes how the binary and ternary relationships can co-exist in a database with same entities using a binary permission rule which may be applied to ternary as well as n-ary relationships.
Attribute
Attribute is the property of an entity that describes it within the database. The attributes form the major portion of the data within database. An attribute that uniquely identifies its entity becomes the primary key (Loton, 2012) of that entity and the one that refers to another entity becomes foreign key of that entity. The same example of StoreEnterprise database may have several attributes describing its Employees entity by attributes Employee number, name,...