Data Definition Language (DDL) Reference Manual

Data Definition Language (DDL) Reference Manual—529431-004
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1 Introduction to DDL
The Data Definition Language (DDL) enables you to define data objects in Enscribe
files and to translate these object definitions to source code for programming
languages and other HP products.
The DDL language has statements to define data objects and commands to control
how the statements are compiled. DDL data objects include:
•
Constants
•
Definitions (for single fields and groups of fields)
•
Records
•
Subsystem Programmatic Interface (SPI) token codes
•
SPI token maps
•
SPI token types
The DDL compiler compiles object definitions and generates any requested output
from the compiled definitions. Depending on which commands you enter, the DDL
compiler builds a dictionary from the definitions, translates the definitions to FUP
commands, or generates object-definition source code in one or more programming
languages.
A dictionary acts as a repository for the DDL definitions. It helps to maintain
consistency so that the same data, regardless of where it is used, is described in the
same way. Although commonly used to describe data in a database, a dictionary can
be used to describe other types of data. For example, Transfer applications (only on G-
series systems) generally use DDL to define and maintain units-of-work. An application
can have more than one dictionary, or the application can maintain all of its data in a
single dictionary. The only restriction is that only one dictionary can reside on a
subvolume.
Subsystems that define SPI messages in a Distributed Systems Management (DSM)
environment must define the SPI message tokens with DDL, optionally add them to a
dictionary, and compile the definitions to C, COBOL, Pascal (on D-series systems),
pTAL, TACL, or TAL code.
This section provides an overview of DDL functionality, including compiling and
translating data definitions, using DDL definitions, creating a dictionary, creating a
database, generating source code, maintaining a dictionary, and examining a
dictionary.