Recuperate each line of a result into a variable ?

Hello,

I would like to know how to recuperate the results of a request.

I read the O'Reilly book about Postgresql and and know there are 2 ways
in PL/pgSQL to do that :

1.
declare
variable type;
select into variable column for table where...

2.
declare
variable table%ROWTYPE
for variable in select * from table where...

What I want to do is to make a multitable request and to recuperate
each line of the result by stocking a number or text into variable

eg with int;
declare
sum int := 0;
for variable in select count(distinct sold), name from books natural
join authors... loop
sum = sum + sum; ...

eg with text
declare
list text := '''':
variable as text;
for variable in select title from books natural join authors... loop
if
variable like ''The%''
list := list || variable.title || ''\n'' ...

Thanks.

C. Tobini