Data Definition Language (DDL) Reference Manual

Introduction to DDL
Data Definition Language (DDL) Reference Manual—529431-004
1-6
Creating a Dictionary
Both Pathmaker dictionaries and dictionaries created from the DDL compiler can be
written to by more than one user at the same time.
Once a dictionary is created, you can enter object definitions in it. If you have a lot of
complex definitions, you probably want to present them in a schema file rather than
entering them interactively.
The schema statements can be submitted to the DDL compiler as an input file in a
noninteractive session or submitted with a SOURCE command in an interactive
session. (You can also enter statements directly in an interactive session.) In each
case, the DDL compiler compiles the object definition statements and, if a dictionary is
open, writes the objects to the dictionary.
Unless suppressed by a NOLIST command, the DDL compiler automatically produces
a compiler listing. By default, the listing is sent to the home terminal of the DDL
compilation process. You can specify a different listing destination in the OUT run
option of the RUN DDL command or in an OUT command.
A dictionary is not actively integrated with the database files or source code it
describes. If you change a dictionary, the DDL compiler does not automatically change
the associated database or source code. Conversely, if you change a database or
source code directly, the associated dictionary is not affected.
Figure 1-2 on page 1-7 shows the steps for building a schema and compiling it into a
dictionary:
1. Run a text editor program and enter DDL statements and, optionally, DDL
commands into an EDIT file. This file contains your schema (it is your schema file).
2. Run the DDL compiler using the schema file as the input file, or run the DDL
compiler interactively, submitting the schema file with a SOURCE command. In
either case, use the DICT or DICTN command to open the dictionary on a
specified volume and subvolume or on the default volume and subvolume.
Optionally, you can specify a print device to receive the compiler listing.