求一个SQL语句

Question

有2个表，结构如下：
TABLE_1
ID          VALUE_1
1           XXXX
2           XXXXTABLE_2
ID          VALUE_2
2           XXXXX
3           XXXXX
要求查出的结果是
ID            VALUE_1              VALUE_2
1             XXXX                 0
2             XXXX                 XXXX
3             0                    XXXX
该怎么写？

Answer 1

select t.id,
       nvl(t1.value_1,0),
       nvl(t2.value_2,0)
from 
   (select id from table_1
   union 
   select id from table_2) t,
   table_1 t1,
   table_2 t2
where t.id = t1.id(+)
and   t.id = t2.id(+);