MySQL实战注意事项（一）求交集

交集

参考链接：mysql取差集、交集、并集

select num FROM(
select u.code_sn as id,u.phone_number as num
from t1 b
left join t2 u
on
b.from_user=u.code_snwhere b.to_account='1000' and
b.json_info like '%09月份%'
union all
select u.code_sn as id,u.phone_number as num
from t1 o
left join t2 u
on o.buyer_code_sn=u.code_sn
where
o.seller_account_code_sn='1000' and
o.json_info like '%09月份%'
)t3 group by num
having count(num)=2

还有一种方法是使用外连接，取空值。

参考链接：【Mysql】求两个表（查询结果）的差集

select id
FROM usertable
LEFT JOIN(
select id as i
from blog
) as t1
ON usertable.id=t1.i
where t1.i IS NULL