PLSQL Function to sort string that's given as parameter - oracle

Question

following issue:
I get a String as such "512, 986, 571, 665" transferred as parameter, basically a set of 3 digit numbers and these need to be returned sorted from highest to lowest.
I have only found answers pertaining such an issue when the String is found in a table and not given as parameter to a function

Answer 1

Here's one option: split input string into rows (that's what subquery in lines #4 - 6 does), and then aggregate them back using listagg with appropriate order by clause (line #3).
SQL> with test (col) as
2 (select '512, 986, 571, 665' from dual)
3 select listagg(val, ', ') within group (order by val) result
4 from (select to_number(trim(regexp_substr(col, '[^,]+', 1, level))) val
5 from test
6 connect by level <= regexp_count(col, ',') + 1
7 );
RESULT
--------------------------------------------------------------------------------
512, 571, 665, 986
SQL>

Answer 2

A programmatic approach would be to use each element in the list as the index of an associative array (so integers only, or it'll break), which will have the effect of sorting it, then loop through the resulting array constructing a new list:
create or replace function sort_number_list
( p_list varchar2 )
return varchar2
as
type aa is table of number index by pls_integer;
sort_tab aa;
sorted_list varchar2(4000);
begin
for i in 1..regexp_count(p_list, ',') +1 loop
sort_tab(regexp_substr(p_list,'[^,]+', 1, i)) := i;
end loop;
for i in indices of sort_tab loop
sorted_list := sorted_list || ', ' || i;
end loop;
return ltrim(sorted_list,', ');
end sort_number_list;
I've used the indices of syntax added in 21c which makes looping around an associative array less verbose. Alternatively you can use the first and next collection methods.

Answer 3

create or replace TYPE t_numlist IS table OF varchar2(32700);
create or replace function sort_str_of_num(p_string in varchar2,p_delimiter in char) return
varchar2 as
v_strnum varchar2(32767):=p_string;
v_delimiter char(1):=p_delimiter;
l_num t_numlist:=t_numlist();
incr integer :=1;
b_bool boolean:= true;
begin
v_strnum := trim(replace(v_strnum,v_delimiter,' '));
loop
l_num.extend;
l_num(incr):= regexp_substr(v_strnum,'[0-9]{1,}');
v_strnum := trim(SUBSTR(v_strnum,instr(v_strnum,' ')+1));
if (instr(v_strnum,' ')+1)=1 then
l_num.extend;
l_num(incr+1):=regexp_substr(v_strnum,'[0-9]{1,}');
exit;
end if;
incr:=incr+1;
end loop;
for i in (select column_value from table(l_num) order by to_number(column_value))loop
if b_bool then v_strnum:=i.column_value;
else v_strnum:=i.column_value||', '||v_strnum;
end if;
b_bool:=false;
end loop;
return v_strnum;
exception
when others then dbms_output.put_line('wrong entry');
end;
This will sort any list of numbers in a string and numbers can have any digit count. Also u can enter any character to be the delimiter between numbers (delimiter must be 1 character) and space character in number list string is ignored.

Answer 4

One way would be to use the ability of xmltable to parse a comma-separated list into XML elements, then use its getstringval() method to convert each element into a string, then finally re-aggregate the strings using listagg:
create or replace function sort_number_list
( p_list varchar2 )
return varchar2
as
sorted_list varchar2(4000);
begin
select listagg(x.column_value.getstringval(), ', ') within group (order by to_number(x.column_value.getstringval()))
into sorted_list
from xmltable(p_list) x;
return sorted_list;
end sort_number_list;
Test:
select sort_number_list('97,3,-123,4')
from dual;
SORT_NUMBER_LIST('97,3,-123,4')
------------------------------------------------------------
-123, 3, 4, 97