从两个表中选择相同ID的最短时间（MySQL）

Question

嗨，我有两个表，并且对于两个表中的同一联系人“电子邮件”，我想知道“电子邮件”的第一次联系。

conversation_and_id

联系人

预期输出

到目前为止，我只做过外部联接来联接两个表，但是它删除了重复的“电子邮件”，我需要它来比较同一“电子邮件”的时差。

ALTER TABLE conversation_and_id CHANGE `email` `conversation_and_id_email` VARCHAR(100);

create table conversation_and_id_and_contact
SELECT *
FROM contact AS con
LEFT JOIN conversation_and_id AS ci ON con.email = ci.conversation_and_id_email
UNION
SELECT *
FROM contact AS con
RIGHT JOIN conversation_and_id AS ci ON con.email = ci.conversation_and_id_email;

create table final
select 
if (f.email is not null, f.email, f.conversation_and_id_email) as email1,
if (f.atlas_interest is not null, f.atlas_interest, f.created_at) as time1,
if (f.conversation_and_id_email is not null, f.conversation_and_id_email, f.email) as email2,
if (f.created_at is not null, f.created_at, f.atlas_interest) as time2
from conversation_and_id_and_contact f;

Answer 1

任何地方的标准解决方案是对两个表执行完全外部联接并获得eyLvv73vv73vv73vv71cdTAwMDBcdTAwMTBKRklGXHUwMDAwXHUwMDAx XHUwMDAxXHUwMDAxXHUwMDAwSFx1MDAwMEhcdTAwMDBcdTAwMDDvv73v v71cdTAwMDBcZkFwcGxlTWFya1xu77+977+9XHUwMDAw77+9XHUwMDAw XHUwMDA3XHUwMDA1XHUwMDA1XHUwMDA2XHUwMDA1XHUwMDA1XHUwMDA3 XHUwMDA2XHUwMDA2XHUwMDA2XGJcdTAwMDdcdTAwMDdcYlxuXHUwMDEx XHUwMDBiXG5cdFx0XG5cdTAwMTRcdTAwMGZcdTAwMGZcZlx1MDAxMVx1 MDAxOFx1MDAxNVx1MDAxOVx1MDAxOVx1MDAxN1x1MDAxNVx1MDAx ... 时间戳。

但是，由于MySQL还不支持完全外部联接，因此您需要对左右联接进行联合以获得所需的结果。最终的[不必要的长]查询如下：

MIN()