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Database Objects
Whilst Tables are the fundamental components of a relational database and allow the definition of Columns, Data Types, Keys and Indexes, there are a number of other Objects that are important in RDBM systems including:
- Views - a View represents the result-set of a pre-defined query; they are dynamically derived from the data stored in one or more Tables (or other Views)
- Procedures - a feature that some DBMS products implement to provide subroutines that can contain one or more SQL statements to perform a specific task such as data validation, access control, or to reduce network traffic between clients and the DBMS servers
- Functions - a feature that some DBMS products implement to provide a mechanism to extend the functionality of the database server; each is a routine that can accept parameters, perform an action (such as a complex calculation) and return the result of that action as a value
- Sequences - a feature that some DBMS products implement to provide a mechanism to generate unique values - the Sequence ensures that each call to it returns a unique value
The UML itself does not specify how data modeling is performed, but Enterprise Architect has a fully integrated UML profile for data modeling and a range of features built in to the core product that will make data modeling easy.
The profile uses stereotypes and Tagged Values to extend standard UML elements into data modeling constructs. This is achieved by adding the database object stereotype to a UML Class; so that you would model:
- Data Modeling diagrams as extended UML Class diagrams
- Tables as UML Class objects with a stereotype of <<table>>
- Views as UML Class objects with a stereotype of <<view>>
- Procedures as UML Class objects with a stereotype of <<procedure>>
- Functions as UML Class objects with a stereotype of <<function>>
- Sequences as UML Class objects with a stereotype of <<dbsequence>>
You can quickly create and configure all of these objects in your database model with Enterprise Architect.