ALTER SESSION SET PLSQL_WARNINGS='ENABLE:ALL'

DECLARE  
  -- Associative array indexed by string:  
   
  TYPE population IS TABLE OF NUMBER   
    INDEX BY VARCHAR2(64);  
  
  city_population  population;  
  i                VARCHAR2(64);   
  
BEGIN  
  -- Add elements (key-value pairs) to associative array:  
  
  city_population('Smallville')  := 2000;  
  city_population('Midland')     := 750000;  
  city_population('Megalopolis') := 1000000;  
  
  -- Change value associated with key 'Smallville':  
  
  city_population('Smallville') := 2001;  
  
  -- Print associative array:  
  
  i := city_population.FIRST;  -- Get first element of array  
   
  WHILE i IS NOT NULL LOOP   
    DBMS_Output.PUT_LINE  
      ('Population of ' || i || ' is ' || city_population(i));   
    i := city_population.NEXT(i);  -- Get next element of array   
  END LOOP;  
END;