当表为空时,我需要创建一个查询来打印警告消息,但如果表为空,它如何打印任何内容?HIVE.hql:
select
x,y,count(*)
from
table1
group by
x,y
having
count(*)=0
好吧,你可以做:
select 'Oops! No rows!
from (select count(*) as cnt
from t
) t
where cnt = 0;
你也可以做:
select 'Oops! No rows'
from t
having count(*) = 0;
然而,我发现没有group by
的having
很尴尬。