我有一张名为customer_transactions的桌子和一张黑名单。customer_transactions表有一个名为atm_name的列。两个表共享一个名为id的唯一键。
如何以查询显示的方式交叉这两个表?
出现在两个表上的
我有这样的东西
SELECT id,
atm_name,
count(atm_name) as atm_count
FROM customer_transactions
GROUP BY id, atm_name如何将此表与黑名单表交叉,并维护当前的输出?
提前谢谢。
发布于 2020-12-10 17:54:35
你好像想加入。假设列id将两个表关联起来,并且它是blacklist中的唯一键,则可以这样做:
select ct.id, ct.atm_name, count(*) as atm_count
from customer_transactions ct
inner join blacklist b on b.id = ct.id
group by ct.id, ct.atm_name您还可以使用exists和相关子查询来表示此逻辑:
select ct.id, ct.atm_name, count(*) as atm_count
from customer_transactions ct
where exists (select 1 from blacklist b where b.id = ct.id)
group by ct.id, ct.atm_namehttps://stackoverflow.com/questions/65239752
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