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Oracle PL/SQL Programming: A Developer's Workbook by Andrew Odewahn, Steven Feuerstein

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Expert

Q:

29-28.

The matches are:

  • 1 and d

  • 2 and b

  • 3 and c

  • 4 and a

Q:

29-29.

There are several possible ways to improve the program. The following optimization eliminates the nested loops by accumulating the schedule in reverse, resulting in a program that is both faster and easier to understand (note that there are several versions on the book’s web page):


/* Filename on web page: presvalue.sql */
PROCEDURE build_lease_schedule
IS
   pv_total_lease NUMBER (9) := 0;
   one_year_pv NUMBER (9) := 0;
BEGIN
   fixed_count := 0;
   var_count := 0;

   FOR year_count IN REVERSE 1 .. 20
   LOOP
      one_year_pv :=
         pv_of_fixed (year_count) +
         pv_of_variable (year_count);
      pv_total_lease :=
         pv_total_lease + one_year_pv;
      pv_table (year_count) :=
         pv_total_lease;
   END LOOP;
END;

Q:

29-30.

You can create an anonymous PL/SQL block within an IF statement to declare and use memory only when necessary:

PROCEDURE only_as_needed (...) IS
BEGIN
   IF <condition>
   THEN
      DECLARE
         big_string VARCHAR2(32767) :=  ten_minute_lookup (...);
         big_list list_types.big_strings_tt;
      BEGIN
         use_big_string (big_string);
         Process_big_list (big_list);
      END;
   ELSE
      /* Nothing big
         going on here */
      ...
   END IF;
END;

Q:

29-31.

You can use native dynamic SQL to easily change the status of a trigger:

 /* Filename on web page: settrig_status.sp */ CREATE OR REPLACE PROCEDURE settrig (tab ...

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