我有一个像这样的关联数组:
continent_population('Australia') := 30;
continent_population('Antarctica') := 90;
continent_population('UK') := 50;
如何在PL / SQL中的值之后对此数组进行排序?谢谢!
答案 0 :(得分:7)
您不能按值对关联数组进行排序,但您必须将数据转换为其他数据结构并在那里进行排序。最简单的方法是转换到另一个关联数组,其中键和值交换位置,但这要求您的键值也应该是唯一的。
以下是适用于Sorting PL/SQL Collections的案例的示例。请查看该文章了解详情。
/* The sorting is done with SQL thus these types have to be SQL types. */
create type sortable_t is object(
continent varchar2(32767),
population number
);
/
create type sortable_table_t is table of sortable_t;
/
declare
type continent_population_t is table of pls_integer index by varchar2(32767);
continent_population continent_population_t;
i varchar2(32767);
sorted sortable_table_t := sortable_table_t();
begin
/* Populate original data. */
continent_population('Australia') := 30;
continent_population('Antarctica') := 90;
continent_population('UK') := 50;
continent_population('USA') := 50;
/* Convert to a helper data type that is used for sorting. */
i := continent_population.first;
while i is not null loop
sorted.extend(1);
sorted(sorted.last) := new sortable_t(i, continent_population(i));
i := continent_population.next(i);
end loop;
/* Show that the content is not sorted yet. */
dbms_output.put_line('Unsorted:');
for j in sorted.first .. sorted.last loop
dbms_output.put_line(sorted(j).continent || ' = ' || sorted(j).population);
end loop;
/* Sorting with SQL. */
select cast(multiset(select *
from table(sorted)
order by 2 asc, 1 asc)
as sortable_table_t)
into sorted
from dual;
/* Show that the content is now sorted. */
dbms_output.put_line('Sorted by value:');
for j in sorted.first .. sorted.last loop
dbms_output.put_line(sorted(j).continent || ' = ' || sorted(j).population);
end loop;
end;
/
打印:
Unsorted:
Antarctica = 90
Australia = 30
UK = 50
USA = 50
Sorted by value:
Australia = 30
UK = 50
USA = 50
Antarctica = 90
答案 1 :(得分:0)
接受的答案已过时。从Oracle 12c开始,只要在包规格中声明了类型,就可以使用TABLE运算符查询关联数组:https://galobalda.wordpress.com/2014/08/02/new-in-oracle-12c-querying-an-associative-array-in-plsql-programs/
您可以按值对关联数组进行排序,而没有可以转换数据: Sorting an index-by table (associative array)