NVL()

The NVL() operator returns the second parameter if the first argument evaluates to NULL.

Syntax

NVL( main-expr, subst-expr )
  1. main-expr and subst-expr are any expression supported by the language.

Usage

The NVL() operator evaluates the first argument, and returns the result if the value is not null, otherwise it returns the second argument.

This allows you to write the equivalent of the following IF statement, in a simple scalar expression:

IF main-expr IS NOT NULL THEN
  RETURN main-expr
ELSE
  RETURN subst-expr
END IF

Example

MAIN
  DEFINE var VARCHAR(100)
  LET var = arg_val(1)
  DISPLAY "The argument value is: ", NVL(var, "NULL")
END MAIN