MySQL wählte alle doppelten Zeilen aus
select t.*
from table t
where exists (select 1 from table t2 where t2.url = t.url and t2.id <> t.id);
Alert Ant
select t.*
from table t
where exists (select 1 from table t2 where t2.url = t.url and t2.id <> t.id);