Introduction to Pathmaker

Tandem Databases and TMF
Introduction to Pathmaker and Pathway
067867 Tandem Computers Incorporated 1–35
Enscribe DDL (Data Definition Language)
Enscribe DDL is one of the Tandem Encompass products. As its name implies, DDL
is a language used to define data. The language consists of:
Statements to define data
Commands to control how those statements are compiled
DDL is also a program that compiles the data definitions and generates output from
the compiled definitions. Depending on which compiler commands are entered, DDL
can do the following:
Build a dictionary from the definitions
Translate record definitions into File Utility Program (FUP) commands
Generate source code that describes data in a variety of programming languages
A DDL dictionary functions as a central repository for the data definitions of an
application. The dictionary 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 DDL data dictionary can
also be used to store information about other kinds of data. For example, application
variables, constants, and screen-only fields can be defined with DDL and have their
definitions maintained in a DDL dictionary.
Creating an Enscribe Database. Enscribe DDL can be used as a language and compiler to
generate FUP commands that can be used to create an Enscribe database. When DDL
is used for this purpose, the person developing the database must specify certain
criteria about the database structure and characteristics. These criteria include:
File structure
Record structure
Data-item characteristics
This information is coded using the data definition language and is usually stored in a
TEDIT file called a schema. A schema is a formal representation of data composed of
DDL statements that describe the data as fields, groups of fields, or records.
The schema is compiled and, if the DDL compiler is directed to generate FUP
commands as output, the results can be used by FUP to generate the actual database.
Note The Pathmaker product provides a utility that can be used to create these FUP commands.