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求教,为了横向连接两个sql,一开始用的fulljoin,结果报错,改成leftjoin就没问题(仅仅full改成left,其他没有动),求教fulljoin和leftjoin编写上哪里的问题
Full join语句:
select a1.city,a1.yici,a2.liangci
from
(select city, count(cishu) as yici
from jituan_ceshi
where cishu ='1.0'
group by city) as a1
full join
(select city,count(cishu) as liangci
from jituan_ceshi
where cishu ='2.0'
group by city) as a2
on a1.city=a2.city
order by a1.city
Left join语句:
select a1.city,a1.yici,a2.liangci
from
(select city, count(cishu) as yici
from jituan_ceshi
where cishu ='1.0'
group by city) as a1
left join
(select city,count(cishu) as liangci
from jituan_ceshi
where cishu ='2.0'
group by city) as a2
on a1.city=a2.city
order by a1.city
a1和a2两个SQL单独运行都能出结果