Dev Corner

DECLARE
  TYPE population_type IS TABLE OF NUMBER INDEX BY VARCHAR2(64);
  country_population population_type;
  continent_population population_type;
  howmany NUMBER;
  which VARCHAR2(64);
 
BEGIN
  country_population('Greenland') := 100000;
  country_population('Iceland') := 750000;
  howmany := country_population('Greenland');
 
  continent_population('Australia') := 30000000;
  continent_population('Antarctica') := 1000; -- Creates new entry
  continent_population('Antarctica') := 1001; -- Replaces previous value
  dbms_output.put_line('Count: ' || continent_population.count);
 
  which := continent_population.FIRST; -- Returns 'Antarctica'
 
-- as that comes first alphabetically.
  which := continent_population.LAST; -- Returns 'Australia'
  howmany := continent_population(continent_population.LAST);
-- Returns the value corresponding to the last key, in this
-- case the population of Australia.
 
  -- Traverse Continents Associative Array
  dbms_output.put_line('Elements in continent_population: ' || continent_population.count);
  which := continent_population.FIRST;
  WHILE which IS NOT NULL LOOP
    dbms_output.put_line(which || ': ' || continent_population(which));
    which := continent_population.NEXT(which);
  END LOOP;
  -- Outputs:
  --   Count: 2
  --   Elements in continent_population: 2
  --   Antarctica: 1001
  --   Australia: 30000000
 
END;

DECLARE
  TYPE CourseList IS TABLE OF VARCHAR2(10);
  courses CourseList := CourseList();
BEGIN
  dbms_output.put_line('Initial count= ' || courses.count ||
                       ', first= ' || courses.first ||
                       ', last= ' || courses.last ||
                       '');
  courses.extend(5);
  dbms_output.put_line('After extend(5) count= ' || courses.count ||
                       ', first= ' || courses.first ||
                       ', last= ' || courses.last ||
                       '');
  dbms_output.put_line('After extend(5) count: ' || courses.count);
 
END;