6.2.3 Tables, Columns, and Data Types

A ColumnSet represents any form of relational data. A NamedColumnSet is a cataloged version of a ColumnSet, which is owned by a Schema. A NamedColumnSet can be a logical View or a physical Table. Instead of being a NamedColumnSet, a ColumnSet can be a QueryColumnSet, which is the result of an SQL query.

Columns are associated with an SQLDataType, using the type association from StructuralFeature to Classifier inherited from ObjectModel Core.

Figure 6-3 shows the original two data types: simple type and distinct type. Simple types are defined by the [SQL] standards, however, some RDBMS implementations use additional types. An SQL distinct type is defined from a simple type.

/constraint /constrainedElementCheckConstraint