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Oracle in a Nutshell
book

Oracle in a Nutshell

by Rick Greenwald, David C. Kreines
December 2002
Intermediate to advanced content levelIntermediate to advanced
928 pages
85h 29m
English
O'Reilly Media, Inc.
Content preview from Oracle in a Nutshell

Forward Declarations

Programs must be declared before they can be used. PL/SQL supports mutual recursion, in which program A calls program B, whereupon program B calls program A. To implement this mutual recursion, you must use a forward declaration of the programs. This technique declares a program in advance of the program definition, thus making it available for other programs to use. The forward declaration is the program header up to the IS/AS keyword:

PROCEDURE perform_calc(year_in IN NUMBER)
IS
   /* Forward declaration for total_cost function. */
   FUNCTION total_cost (...) RETURN NUMBER;

   /* The net_profit function can now use total_cost. */
   FUNCTION net_profit(...) RETURN NUMBER
   IS
   BEGIN
      RETURN total_sales(...) - total_cost(...);
   END;

   /* The Total_cost function calls net_profit. */
   FUNCTION total_cost (...) RETURN NUMBER
   IS
   BEGIN
      IF net_profit(...) < 0
      THEN
         RETURN 0;
         ELSE
         RETURN...;
      END IF;
   END;
BEGIN /* procedure perform_calc */
   ...
END perform_calc;
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Publisher Resources

ISBN: 0596003366Errata Page