sql：两个表查到的数据取合集/交集

①取合集

select id from 
(
    select id from A
    UNION
    select id from B
)ti

UNION会自动去重

②取交集

select id from 
(
    select id from A
    UNION ALL
    select id from B
)ti group ti.id having count(id)>1


UNION ALL 不会自动去重

或

select id from
(
    select id from A
)ti 
and id in (select id from B) 

欢迎指正~