Mysql从两个表中选择，获取所有数据，如果不存在则num 0

Question

表a:

name
a
e

表b:

name   num
   a    10
   b    20
   c    30

我想要得到:

name    num
a   10
b   20
c   30
e   0

我的sql语句是:

select c.name,
IFNULL (b.num,0) as 'num'
from
(select name from a
union 
select name from b) c
left join b
on c.`name`=b.`name`

还有其他方法可以更简单地得到这个结果吗？

Answer 1

FULL OUTER JOIN can be achieve by below in mysql 

SELECT a.name, IFNULL (b.num,0) as 'num' FROM a
LEFT OUTER JOIN b ON b.name = a.name
UNION
SELECT b.name, IFNULL (b.num,0) as 'num' FROM a
RIGHT OUTER JOIN b ON a.name = b.name