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Articles and References

Conceptual, Logical, Physical Data Models and Process Models

Nested relations


Normal forms


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Database design, application design and business process design are a combination of art and science, but software tools simplify the process. Database administrators (DBAs) and developers exploit tools to elevate their design skills. They use data modeling tools to create and refine conceptual, logical and physical models. The use object modeling tools to design application objects and business process modeling tools to specify the flow business processes.

Technologies for modeling applications have continuously evolved for several decades. The successors to the flowcharts and data flow diagram (DFD) are Peter Chen's Entity-Relationship Diagramming (ERD), Terry Halpin's Object-Role Modeling (ORM) and the Three Amigos' Unified Modeling Language (UML). The Three Amigos (Grady Booch, Ivar Jacobson, James Rumbaugh) were the inventors of UML, but it is now a specification from Object Management Group (OMG),

Featured Links

Modeling SQL and Multidimensional Data
Ken North

This article discusses CWD4ALL, a data modeling product supports the design on SQL and multidimensional databases.

Michael David

What makes this paper of significant importance to the SQL/XML industry is it proves how standard SQL can perform full multi-leg hierarchical processing. It explains how the relational Cartesian processing engine automatically and inherently performs Lowest Common Ancestor (LCA) logic that's required to perform hierarchical processing. This is original material.

This paper also points out that XQuery cannot perform multi-leg query processing automatically, but requires complex procedural hierarchical processing programming that must include the Lowest Common Ancestor logic which is very complex in itself. This paper identifies other XML query products that are being built on top of XQuery to support non-procedural multi-leg processing.

Papers and Articles

Data Schema Normalization
Scot Becker

This white paper explains normal forms and discusses their relationship to ORM data modeling.

Dimensional Data Models versus Entity Relationship Models: Does it Make a Difference to End Users?
Karen Dowling, Robert St. Louis (Arizona State), David Schuff (Temple)

This paper examines which modeling technique is better for user understanding and  recall of model details. The researchers compared whether a dimensional data model is easier to remember than an entity-relationship model.

Peter Pin-Shan Chen

Abstract: A data model, called the entity-relationship model, is proposed. This model incorporates some of the important semantic information about the real world. A special diagrammatic technique is introduced as a tool for database design. An example of database design and description using the model and the diagrammatic technique is given. Some implications for data integrity, information retrieval, and data manipulation are discussed. The entity-relationship model can be used as a basis for unification of different views of data: the network model, the relational model, and the entity set model. Semantic ambiguities in these models are analyzed. Possible ways to derive their views of data from the entity-relationship model are presented. 

Formal and conceptual models for XML structures - the past, present and future
Arijit Sengupta, Sriram Mohan

The authors surveyed and classified ten data models, (DOM, XQuery, SAL, UML) and propose Heterogeneous Nested Relations as an appropriate data model for XML.

Peter Pin-Shan Chen

This paper discusses several important future research directions in conceptual modeling.

Join Constraints
Terry Halpin 

This paper discusses how UML, ORM, OSM, and ER modeling support conceptual joins (objects playing roles in two relationships).

Modeling, Metadata, and XML
Ken North

UML and ORM are obviously modeling technologies, but where does XML fit into the picture? 

Esko Marjomaa

Abstract. The questions of quality may be divided into four distinct classes, namely, ontological, epistemological, value-theoretical, and pragmatic. However, there are plenty of important problems the solutions of which have bearings on the different classes. Some of the problems are very tricky, and we shall explore two of them, (1) How does the basic ontology affect the form and content of the resulting conceptual model?, and (2) What is the status of formalization in pragmatics? There are good reasons to claim that the answers to these questions in great deal also settle the other ones.

Modeling and Querying Recursive Data Structures
J.H. ter Bekke and J.A. Bakker 

Abstract: Present recursive applications for recursive data structures require complex software packages; they cannot be specified in a declarative query language. Recursive queries are complex when a kind of data modeling is applied that emphasizes variable relationships instead of definite and inherent (structural) relationships: users must specify processing details as navigation and iteration.

Another kind of modeling supports definitive relationships; an example is the relational model. Although this kind of modeling makes control statements in queries superfluous, the relational model still creates problems for end users because relationships between tables cannot be specified inherently; they are specified by relationships between key attributes: subset constraints. Consequently, a user interested in data from diverse tables has to specify join operations, which offers opportunities for semantic errors such as joining over non-key attributes.

Also semantic data modeling is based on definitive relationships, but contrary to the relational model it enables us to specify data structure in an inherent way. As a consequence join terms are superfluous: processing details can be derived by a software system interpreting semantic metadata. Using family trees as an example, we compare the consequences of the two categories of data modeling mentioned above for the specification of non-recursive queries, whereas the following paper will show that inherent specification of data structure is also a fundamental prerequisite for the declarative specification of recursive operations. The resulting processing is reliable and efficient as can be demonstrated by a working database management system.

Unified Modeling Language (UML) and Object-Role Modeling (ORM)
Terry Halpin

Dr. Halpin discusses the Unified Modeling Language (UML) within the context of Object Role Modeling (ORM) and shows how ORM models can be used in conjunction with UML models.

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