This chapter describes the Data Definition Language (DDL) of GDL. It is founded on the data model GDM described in the previous chapter. The DDL is used to define the structure, the integrity constraints and views of a schema. It also supports schema evolution. GDL allows the construction of temporary record types and link types that exist only during a single session or run. We say that these objects are volatile. Volatile record and link types are described in Chap. 4. The record and link types that reside in the database are said to be resident. DDL supports definitions of resident record and link types.
KeywordsIntegrity Constraint Link Type Record Type Record Occurrence Storage Operation
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