Dieses PL/SQL sollte es tun:
declare
l_cols long;
l_sql long;
begin
for r in (select column_name from all_tab_columns
where table_name = 'TABLEA'
and owner = 'SCHEMA1'
)
loop
l_cols := l_cols || ',' || r.column_name;
end loop;
-- Remove leading comma
l_cols := substr(l_cols, 2);
l_sql := 'insert into schema1.tableA (' || l_cols || ') select '
|| l_cols || ' from schema2.tableA';
execute immediate l_sql;
end;
/