The basic object-oriented paradigm has two major ways to relate objects, distinct from any logical data relationships that might be included in a pure object-oriented database: inheritance and composition. The classes in an object-oriented environment aren't always independent. Harrington, in SQL Clearly Explained (Third Edition), 2010 Class Relationships CASE tools for active data warehousing, decision support, and XML data modeling are available in today's marketplace. Examples of the most prominent of these tools, shown in this chapter, are: 1.Ĭomputer Associates' AllFusion ERwin Data Modeler 3.
The best CASE tools for database design are those that are integrated with a complete suite of application tools that cover the entire software development life cycle. Use higher-end tools for more complex tasks such as schema evaluation, UML design, reverse engineering, multiperson team support, integration with other software development tools, design compliance checking, or reporting $100 range) if you only want to do ER modeling. Obtain automatic reporting and reverse engineering capability. 2.Īutomatically transform a logical design into SQL table definitions or other data definition language constructs. The chief motivations for selecting and using CASE tools are: 1.ĭesire to dramatically reduce the complexity of conceptual and logical designs. Database designers are strongly encouraged to use one of the powerful and feature-rich CASE tools for developing logical database designs and transitioning them into physical databases they can use. Because each item name begins with “Relation,” all relationship entries sort together in the data dictionary. Each relationship in the related ERD also has an entry. (Of course, you can’t see the colors in this black-and-white book, so you’ll have to take my word for it.) Domain names appear alphabetically among the entities. Entity names are red attributes are blue. In the CASE tool used for examples in this chapter, entities are organized alphabetically, with the attributes following the entity name. The layout of a data dictionary varies with the specific CASE tool, as does the way in which entries are configured. In addition, by linking entries in the ER diagram to the data dictionary you can provide enough information for the CASE tool to generate the SQL CREATE statements needed to define the structure of the database.
Since you were introduced to several types of ER diagrams in Chapter 4, we will not repeat them here, but instead focus on the interaction of the diagrams and the data dictionary.Ī data dictionary provides a central repository for documenting entities, attributes, and domains. Harrington, in Relational Database Design and Implementation (Fourth Edition), 2016 The Data Dictionaryįrom a database designer’s point of view, the ER diagram and its associated data dictionary are the two most important parts of CASE software.