Relation between rows ranking - mysql

Question

I have a table that looks like this:
If there is any relationship between the imported and section then they should be grouped together. Depending on the relationship they should be grouped as 1,2,3,4,....
I tried a query that looks like this:
select sec.section,sec.id, sec.imported, sec.id,
case when imp.imported = sec.section or imp.imported is null then 1 ELSE
2 end as rn
from
( select section, id, imported from temp1) sec
left outer join
(
select imported, Section from temp1
) imp on imp.imported = sec.section
But in this scenario my rn is always 1. Can you help me review this query?
I'm not sure how to go around this. Do we need to use a while loop and do it or can this be done using a query?
Example creation script:
create table temp1 (
id int, imported int, section int, rn int, checked int default 0
);
insert into temp1(id, section, rn) values (204, 718, 0);
insert into temp1(id, imported, section, rn) values (997,718,034,0);
insert into temp1(id, imported, section, rn) values (998,034,055,0);
insert into temp1(id, imported, section, rn) values (111,453,234,0);
insert into temp1(id, section, rn) values (908, 453,0);
insert into temp1(id, imported, section, rn) values (231,234,890,0);
insert into temp1(id, section, rn) values (342, 567,0);
My End Result should look like:
I'have tried with while loop too creating a stored procedure:
DROP PROCEDURE IF EXISTS sp_recursiveimport;
Delimiter $$
CREATE PROCEDURE sp_recursiveimport() -- (IN rnX integer)
BEGIN
DECLARE n INT DEFAULT 0; DECLARE i,j,k INT DEFAULT 0; SELECT COUNT(*) FROM temp1 INTO n;
SET i=0; set #rn = 1; -- set #k = 0;
WHILE i<n DO
set j = 0; select i;
set #sec = (select ifnull(section,0) FROM temp1 LIMIT i,1);
set #imp = (select ifnull(imported,0) FROM temp1 LIMIT i,1); select #imp, #sec;
update1: while j<n do select j;
-- if j=0 then
if (select ifnull(imported,0) from temp1 limit j,1) = #sec and (select checked from temp1 limit j,1) = 0 then
set #update = concat('update temp1 set rn = 1, checked = 1 where imported = ',#sec); select #update; PREPARE stmt_name FROM #update; EXECUTE Stmt_name; DEALLOCATE prepare stmt_name;
set #update1 = concat('update temp1 set rn = 1, checked = 1 where section = ',#sec); select #update1; PREPARE stmt_name FROM #update1; EXECUTE Stmt_name; DEALLOCATE prepare stmt_name;
set k = j;
end if;
if (select ifnull(section,0) from temp1 limit j,1) = #imp and (select checked from temp1 limit j,1) = 0 then
set #update3 = concat('update temp1 set rn = 1, checked = 1 where section = ',#imp); select #update3; PREPARE stmt_name FROM #update3; EXECUTE Stmt_name; DEALLOCATE prepare stmt_name;
set #update4 = concat('update temp1 set rn = 1, checked = 1 where imported = ',#imp); select #update4; PREPARE stmt_name FROM #update4; EXECUTE Stmt_name; DEALLOCATE prepare stmt_name;
set k = j;
end if;
-- set #sec = (select ifnull(imported,0) from temp1 limit k,1);
-- set #imp = (select ifnull(section,0) from temp1 limit k,1); select #sec, #imp;
set j= j+1;
end while update1;
set i = i + 1;
END WHILE;
END;
$$
delimiter;
Not sure why its not working.

Answer 1

This is not an answer to the question since, honestly, I don't know how to write this query in MySQL 5.x.
Anyway, at least I wanted to document the answer using recursive CTEs, available on MySQL 8.0 or newer. Here it is:
with recursive sect as (
select id, imported, section, row_number() over() as rn
from temp1 where imported is null
union all
select t.id, t.imported, t.section, s.rn
from temp1 t
join sect s on t.imported = s.section
)
select * from sect order by rn;
Result:
id imported section rn
--- -------- ------- --
998 34 55 1
204 <null> 718 1
997 718 34 1
231 234 890 2
908 <null> 453 2
111 453 234 2
342 <null> 567 3