PATTERNS OF DATA MODELING- P51 pptx

... intent. role one end of a relationship. scenario the execution of a state diagram for an entity of the state diagram’s entity type. schema the structure of the data in a database. seed model ... end. referential integrity a database mechanism that ensures that data references really exist and that there are no dangling foreign keys. relational database a database in which the dat...

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...

Ngày tải lên: 05/07/2014, 06:20

... 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. •...

Ngày tải lên: 05/07/2014, 06:20

... node name could also be invariant over time (candidate key of nodeName alone). Note that the handling of time reflects a limitation of relational DBMSs. It would be better to use time intervals ... Changing over Time Template 53 in a use of the template. A Node is a position within a directed graph. The distinction be- tween parent and child causes the sense of direction that effect...

Ngày tải lên: 05/07/2014, 06:20

... Nodes were important. A UDG (undirected graph) is a set of nodes and a set of edges that connect nodes. You need not show UDG in a use of the template. A Node is an entity type whose records ... cannot handle edges that connect twice to the same node. A UDG (undirected graph) is a set of nodes and a set of edges that connect nodes. (Note: in an undirected graph all the nodes need no...

Ngày tải lên: 05/07/2014, 06:20

... enter data 170 Chapter 13 / Softcoded Values A SoftcodedVal ue is a piece of data for an Entity and has parallel fields for different data types. A SoftcodedValue can have one of four data types—integer, ... softcoded values. The model combines data and metadata. The top entity types shaded in gray (EntityType, Attribute, EnumValue) concern metadata . The bottom (Entity, Softcod...

Ngày tải lên: 05/07/2014, 06:20

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...

Ngày tải lên: 05/07/2014, 06:20

... 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...

Ngày tải lên: 05/07/2014, 06:20

... 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....

Ngày tải lên: 05/07/2014, 06:20