【已解决】如何把两个表相同字段的值相加？

Question

如题所述

Answer 1

先合并，再group相加，这是我的办法：mysql>
select
*
from
c;+------+------+|
id
|
num
|+------+------+|
a
|
10
||
b
|
20
|+------+------+2
rows
in
set
(0.00
sec)mysql>
select
*
from
d;+------+------+|
id
|
num
|+------+------+|
a
|
20
||
b
|
30
|+------+------+2
rows
in
set
(0.00
sec)mysql>
mysql>
mysql>
select
id,sum(num)
from
(select
*
from
c
union
select
*
from
d)tablename
group
by
id;+------+----------+|
id
|
sum(num)
|+------+----------+|
a
|
30
||
b
|
50
|+------+----------+2
rows
in
set
(0.00
sec)