PATTERNS OF DATA MODELING- P41 pdf

... Area 191 An Entity is a thing with semantic meaning. Examples of Entities include a data flow in a data flow diagram and a piece of equipment in an equipment flow diagram. An Entity can be represented ... are helpful for some kinds of models and unnecessary for others. If a diagram omits Ports , then connections go directly to Entities. An EntityType is a classification of Entitie...

Ngày tải lên: 05/07/2014, 06:20

... expertly building data models. This book focuses on databases and not on programming, because most commercial software is built around a database. The database representation (the data model) sets ... scope, and set the xiv Preface key abstractions in the software. These tasks revolve around models and often data mod- els. The skillful use of patterns is intrinsic to building qualit...

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... different data without updating the schema. With user-defined fields, data lacks a description of its meaning. Mislabeled fields are worse, as the description is misleading. • Binary fields. Some databases ... You should be suspicious of tables with zero records. 8.3 Disguised Fields Antipattern 8.3.1 Observation The name and documentation for a field do not indicate the kind of da...

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... Spanish, and Chinese. Data can often be stored in the language of entry, but there is a need to translate metadata, such as labels in forms and reports. Chapter 13 covers softcoded values. The ... values can be softcoded — metadata specifies the intended model and generic tables store the values. Softcoded values are appro- priate for applications with uncertain data structure; softcodi...

Ngày tải lên: 05/07/2014, 06:20

Ngày tải lên: 05/07/2014, 06:20

... Modeling Notation 1 1.3 What Is a Pattern? 2 1.4 Why Are Patterns Important? 3 1.5 Drawbacks of Patterns 4 1.6 Pattern vs. Seed Model 4 1.7 Aspects of Pattern Technology 5 1.8 Chapter Summary 6 Bibliographic ... Summary 89 Bibliographic Notes 89 References 90 Chapter 7 Summary of Templates 91 Part II: Antipatterns 95 Chapter 8 Universal Antipatterns 97 8.1 Symmetric Relationship Ant...

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... chapter starts with a discussion of models and then introduces the topic of patterns. 1.1 What Is a Model? A model is an abstraction of some aspect of a problem. Most software models are expressed as ... combinations. Patterns provide a higher level of building blocks than modeling primitives. Patterns are prototypical model fragments that distill the knowledge of experts. •...

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... Software Architecture: A System of Patterns. Chichester, United Kingdom: Wiley, 1996. [Chen-1976] PPS Chen. The entity-relationship model—toward a unified view of data. ACM Transac- tions on Database ... Vlissides. Design Patterns: El- ements of Reusable Object-Oriented Software. Boston, Massachusetts: Addison-Wesley, 1995. [Hay-1996] David C. Hay. Data Model Patterns: Conventions...

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... the sequence of types in the levels of the hierarchy. • Simple tree. Restricts nodes to a single tree. Treats nodes the same. Use when tree de- composition is merely a matter of data structure. • ... context. Figure 2.11 shows an excerpt of this book’s file structure where I have kept old copies of files from reviews. File names are unique within the context of their directory....

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... branch nodes. A Tree is a hierarchy of nodes and has one node as the root. A particular node may, or may not, be the root. You need not show Tree in a use of the tem- plate. A Node is either ... nodes each of which, in turn, can be a leaf node or a further branch node. Figure 2.18 adds the constraint that a tree cannot have any cycles. (See Section 2.2.1 for an explanation of cycles.)...

Ngày tải lên: 05/07/2014, 06:20