XML Schema Complete Reference, The

24.13. group Element

The group element typically allows a global model group to be used in a complexType through the ref attribute. The global group is a choice element, sequence element, or all element that can be used in numerous complex types. A database designer has two major options in designing a schema for using a group:

• Subsume the group into the table(s) that refer to the group.

• Create a separate table or series of tables to represent the group and refer to the group when needed through a foreign key relationship.

Each of these approaches has merits. The first approach is best when the group can be mapped directly to a series of table columns and the group itself is not the source of numerous queries. For example, Listing 24.13 demonstrates ...