Můžete to udělat pomocí union all
a group by
:
select url,
max(id1) as id1, max(id2) as id2, . . .
from ((select url, id as id1, NULL as id2, . . . from table1) union all
(select url, NULL as id1, id as id2, . . . from table1) union all
. . .
) t
group by url;