PLS-00103: Encountered the symbol "=" when expecting one of the following.... in PL/SQL script - sql

Question

create or replace function lstnation (listdisplay in varchar2)
return varchar2 is
nName varchar2 (1000) default null;
listD varchar2(1000) default null;
cursor display_nation
is
select nation.n_name
from nation
inner join region
on region.r_regionkey = nation.n_nationkey
where region.r_regionname = listdisplay;
BEGIN
open display_nation;
loop
fetch display_nation into nName;
exit when display_nation%notfound;
IF
listD := listD || RTRIM(nName)||' , ';
end loop;
close display_nation;
return listD;
end lstnation;
/
DECLARE
rKey region.r_regionkey%type;
rName region.r_name%type;
nList varchar2(1000);
cursor outer_block is
select region.r_regionkey, region.r_name, lstnation(region.r_name)
from region;
BEGIN
open outer_block;
loop
fetch outer_block into rKey, rName, nList;
exit when outer_block%notfound;
dbms.output.put_line(rkey || ' ' || RTRIM(rName) || ': '|| nList);
end loop;
close outer_block;
end;
/
I get two errors, how can I fix it
LINE/COL ERROR
19/12 PLS-00103: Encountered the symbol "=" when expecting one of the
following:
. ( * # % & = - + < / > at in is mod remainder not rem then
<an exponent (**)> <> or != or ~= >= <= <> and or like like2
like4 likec between || multiset member submultiset
20/2 PLS-00103: Encountered the symbol "END" when expecting one of the
following:
begin function pragma procedure subtype type
current cursor delete
exists prior

Answer 1

You can save some coding and efficiency by replacing the cursor loop with the listagg function
select listagg(rtrim(nation.n_name),',')
from nation
inner join region
on region.r_regionkey = nation.n_nationkey
where region.r_regionname = listdisplay;
So that will collate all the matching rows, and use whatever delimiter is passed in. One thing to be aware of, you have listD varchar2(1000) so as long as the results from the query are less than 1000, you are OK. If you expect a larger result set, you may need to increase or use a clob.
If for some reason, you still want to use the loop method, then you need to fix your IF statement:
loop
fetch display_nation into nName;
exit when display_nation%notfound;
IF <condition> THEN
listD := listD || RTRIM(nName)||' , ';
END IF;
end loop;