Null Substitution

How to:

Define a Null Word

With a null substitution, you can use more than one word to represent a phrase. By using more than one word in a request instead of a single word, you can make the request more readable.

You can define a null word using LET. A null word is ignored by the application.

Syntax: How to Define a Null Word

To define a null word, issue the command

LET word=;

Example: Defining a Null Word

This LET command defines DISPLAY as a null word:

LET
DISPLAY=;
AVESAL = SUM AVE.SALARY BY DEPARTMENT
END

In the following request, the word DISPLAY is used in the code DISPLAY AVESAL, for readability, to make clear that the request prints the value represented by AVESAL:

TABLE FILE EMPLOYEE
DISPLAY AVESAL
WHERE DEPARTMENT IS 'PRODUCTION'
END

The word DISPLAY is ignored and the request is translated as:

TABLE FILE EMPLOYEE
SUM AVE.SALARY BY DEPARTMENT
WHERE DEPARTMENT IS 'PRODUCTION'
END