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, infor-mation retrieval, and data manipulation are discussed. The entity-relationship model can be used as a basis for unification of different views of data: t,he 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. Key Words and Phrases: database design, logical view of data, semantics of data, data models, entity-relationship model, relational model, Data Base Task Group, network model, entity set

Data modelling reveals the internal structure of an information system, abstracting away from details of the physical representation. We show that entity-relationship modelling, a well-tried example of a data-modelling technique, can be applied to both interactive and non-interactive information artefacts in the domain of HCI. By extending the conventional ER notation slightly (to give ERMIA, Entity-Relationship Modelling for Information Artefacts) it can be used to describe differences between different representations of the same information, differences between user's conceptual models of the same device, and the structure and update requirements of distributed information in a worksystem. It also yields symbolic-level estimates of Card et al.'s (1994) index of `cost-of-knowledge' in an informa- tion structure, plus a novel index, the `cost-of-update'; these symbolic estimates offer a useful complement to the highly detailed analyses of time costs obtainable from GOMS-like...

Data modeling is an essential part of the software development process, and together with application modeling forms the core of the model-driven approach to software engineering. While UML is considered the standard for application modeling, there is really no corresponding open standard for data modeling. In this paper, we propose an approach and a tool to help bridge the gap between application and data modeling based on source transformation technology. The tool, called SQL2XMI, automatically transforms an SQL schema into a UML-ER model expressed in XML Meta Interchange (XMI) 2.1. By bringing the data model to the UML world, both data and application models can be manipulated using the same UML-based tools. 1

This paper describes a category theory semantics for conceptual data modeling. The conceptual data modeling technique used can be seen as a generalization of most existing conceptual data modeling techniques. It contains features such as specialization, generalization, and power types. The semantics uses only simple category theory constructs such as (co)limits and epi- and monomorphisms. Therefore, the semantics can be applied to a wide range of instance categories, it is not restricted to topoi or cartesian closed categories. By choosing appropriate instance categories, features such as missing values, multi-valued relations, and uncertainty can be added to conceptual data models. R'esum'e Cette contribution d'ecrit une s'emantique fond'ee sur la th'eorie des cat'egories et d'evelopp'ee en vue d'une mod'elisation conceptuelle des donn'ees. On peut concevoir la technique ici utilis'ee de mod'elisation conceptuelle des donn'ees comme une g'en'eralisation de la plupart des techniques e...

It is often useful to get high-level views of datasets in order to identify areas of interest worthy of further exploration. In relational databases, the high-level view can be described using Entity-Relationship diagrams, which identify relationships between entities in the data model. Such high-level views are useful for database design activities, and can be used to generate user interfaces for constructing queries. This research introduces techniques for visualizing structural similarity of database queries. We demonstrate that individual queries can be visualized using graph visualization techniques. A distance measure based on query structure is proposed that provides database designers and administrators with a high-level perspective of relationships in the underlying data.

Data modelling reveals the internal structure of an information system, abstracting away from details of the physical representation. We show that entity-relationship modelling, a well-tried example of a data-modelling technique, can be applied to both interactive and non-interactive information artefacts in the domain of HCI. By extending the conventional ER notation slightly (to give ERMIA, Entity-Relationship Modelling for Information Artefacts) it can be used to describe differences between different representations of the same information, differences between usersconceptual models of the same device, and the structure and update requirements of distributed information in a worksystem. It also yields symbolic-level estimates of Card et al.s (1994) index of cost-of-knowledge in an information structure, plus a novel index, the cost-of-update; these symbolic estimates offer a useful complement to the highly detailed analyses of time costs obtainable from GOMS-like models. We conclude that, as a cheap, coarse-grained, and easy-to-learn modelling technique, ERMIA usefully fills a gap in the range of available HCI analysis techniques.

In this paper an Articulated Entity Relationship (AER) diagram is proposed, which is an extension of Entity Relationship (ER) diagram to accommodate the Functional Dependency (FD) information as its integral part for complete automation of normalization. In current relational databases (RDBMS) automation of normalization by top down approach is possible using ER diagram as an input, provided the FD information is available independently, meanwhile, through user interaction. Such automation we call partial and conditional automation. To avoid this user interaction, there is a strong need to accommodate FD information as an element of ER diagram itself. Moreover, ER diagrams are not designed by taking into account the requirements of normalization. However, for better automation of normalization it must be an integral part of conceptual design (ER Diagram). The prime motivation behind this paper to design a system that need only proposed AER diagram as a sole input and normalize the database up to a given normal form in one go. This would allow more amount of automation than the current approach. Such automation we call as total and unconditional automation, which is better and complete in true sense. As the proposed AER diagram is designed by taking in to account the normalization process, normalization up to Boyce Codd Normal Form (BCNF) becomes an integral part of conceptual design. Additional advantage of AER diagram is that any modifications (addition, deletion or updation of attributes) made to the AER diagram will automatically be reflected in its FD information. Thus description of schema and FD information is guaranteed to be consistent. This cannot be assured in current approach using ER diagrams, as schema and FD information are provided to the system at two different times, separately.

Data modeling is an essential part of the software development process, and together with application modeling forms the core of the model-driven approach to software engineering. While UML is considered the standard for application modeling, there is really no corresponding open standard for data modeling. In this paper, we propose an approach and a tool to help bridge the gap between application and data modeling based on source transformation technology. In this paper we introduce SQL2XMI, a tool that automatically transforms an SQL schema into a UML-ER model expressed in XML Meta Interchange (XMI) 2.1, which is specifically designed to support interchange of UML models. By bringing the data model to the UML world, our tool enables the manipulation and integration of both data and application models using the same UML-based tools in an interoperable way. While SQL2XMI was initially created to support our work in software comprehension, the approach we have used can be generalized to recover a rich UML-ER model from any SQL schema to any XMI 2.x format, and can easily be extended to support code engineering by automatically generating SQL schemas from an XMI 2.x file. 1