Hence, in FEM, we add a redundant one-to-manyĪssociation and intersection class, and another level of SQL, and does not provide the constraint column ordinals needed for Modeled as objects contained by a Table and with directĪssociations to the constrained columns (as subclasses of (Foreign keys, check constraints other than NOT NULL,Īnd assertions are not yet supported.) In CWM, these constraints are Where upper(topic_name) like '%BREAKFAST%' Īnd the corresponding object diagram (ignoring columns):īesides views, other kinds of dependencies are recorded by Farrago,īut the rest are not covered by this document.įarrago currently supports primary keys and unique keys asĬonstraints. Select bloggers.name as blogger_name,topics.name as topic_name Consider this addition toīlogger_id int not null references bloggers(id), To hold all dependencies, and only direct dependencies are recorded Here is a class diagram for the view body and dependencies:Ī single instance of class Dependency is created per view We have already seen how view columns are SQL views have a body (an underlying query), result columns, andĭependencies on objects referenced by their body (e.g. Identity columns have a sequence component (not shown) as described in AutoincrementColumns. The initialValue attribute is used to storeĪny DEFAULT value (the Expression class is covered in the The information associated with a single column is modeled via attributesĭetails of allowed datatypes are covered in a later May be used for a table's containment of non-column objects such as Namespace, the ElementOwnership association Instead, the more specific ClassifierFeature association Not used to model the containment of columns by a table Note that the generic ElementOwnership association is Here is a corresponding object diagram for the previous example: NamedColumnSet, and differentiates between columns of In particular, FEM defines tables and views as descendants of The more abstract notion of a class and its attributes: The association between a NamedColumnSet and theĬolumn objects which define its structure is modeled on Meaning extension models can define their own first-class objectsīeyond the standard ones by inheriting from ModelElement.ĬWM refers to any table-like object as a NamedColumnSet. Note that any ModelElement can be contained in a schema, LOCALDB catalog, which already exists) and linked: Would be created (or referenced in the case of the Then (ignoring columns for the moment) the following object instances The ElementOwnership association is used to model bothĬatalog/schema and schema/object containment. Using the Namespace/Package constructs inherited from CWM: Hierarchy: catalogs contain schemas, and schemas contain objects suchĪs tables, views, and procedures. In SQL, first-class objects are defined in a three-level containment Illustrating them via static structure UML class and object diagrams.Īttributes are not always shown unless they are relevant to the In this document, we walk through the submodel areas covered by FEM, Likewise, a CWM import mechanism may be provided which fills in Strip out all FEM-specifics, and produce a valid CWM XMI export. To provide a "slicing" mechanism which can take a set of FEM objects, Where interoperability is desired, we plan Inappropriate for the deep specialization required by Farrago, so we Tag mechanism (to further the goal of interoperability), but tags are The CWM standard recommends that specialization be implemented via the FEM specializes a subset ofĬWM (hiding irrelevant submodels) with specifics from SQL and Farrago. Up-to-date with the latest SQL standards. In some areas, it is very generic and not The metamodel defined by CWM sprawls over a large number of data
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