根据下面的三个表,我将如何产生预期的结果?
Table 1
ID Count A
-----------------
1 1
2 2
Table 2
ID Count B
-----------------
1 3
3 4
Table 3个
ID Count C
-----------------
2 5
4 6
Result个
ID Count A Count B Count C
-----------------------------------
1 1 3
2 2 5
3 4
4 6
我试过
select a.id, a.count_a, b.count_b, c.count_c
from a
full outer join b
on a.id = b.id
full outer join c
on a.id = c.id
or b.id = c.id
和
select id, count_a
from a
union
select id, count_b
from b
union
select id, count_c
from c
但我意识到我不知道如何做一些看似简单的事情.