Oracle PL/SQL集合关联数组

Hi,

In the below example for Associative Array Indexed by String,
set serveroutput on;
DECLARE
-- Associative array indexed by string:
TYPE population IS TABLE OF NUMBER -- Associative array type
INDEX BY VARCHAR2(64); -- indexed by string
city_population population; -- Associative array variable
i VARCHAR2(64); -- Scalar variable
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;
/

OP:
PL/SQL procedure successfully completed.

Population of Megalopolis is 1000000
Population of Midland is 750000
Population of Smallville is 2001

/
What ever the values I change for city_population the FIRST element of this array remain the same to 
'Population of Megalopolis is 1000000'

I dono why.

My problem here is about this line "city_population.FIRST;" here the FIRST keyword refers too.. it refers too highest value associated with elements or ?? the reason is every time I run this block with different combinations I get Megalopolis as output. 

Sorry for the confusion. Please do let me know if any clarifications again!

Thanks

你是什么意思 “我为城市人口改变了什么值”

你给了我们你的代码-太好了。但是你需要给我们举一个例子，说明你在哪里遇到了你的问题。

=

“第一” 按索引顺序排列为第一。

因此，“Megalopolis” 的排序低于 “Midland”，后者低于 “Smallville”

如果我用索引 “Aardvark” 创建了一行，它将首先出现。

索引不是添加数据的顺序，而是varchar值排序的顺序。