我有这个链接两个表的MySQL查询。我想加入主题,从哪里得到不存在的数据从另一个表。我想从两个表中得到不存在的数据
这个在这里得到注册日期为用户
SELECT
t2.name ,phone
FROM
(SELECT name,tid,date_d,class_time AS 'absent'
FROM absent where date_d = '2016-12-04') t1
JOIN
(SELECT name, id,phone AS 'phone'
FROM users ) t2
ON t1.tid = t2.id
group by id
我想谁没有在表t1从表中的两 注册用户我用同样的上述查询,但像这样的东西ON t1.tid != t2.id
它仅适用于不重复的日期
SELECT
t2.name ,phone
FROM
(SELECT name,tid,date_d,class_time AS 'absent'
FROM absent where date_d = '2016-12-04') t1
JOIN
(SELECT name, id,phone AS 'phone'
FROM users ) t2
ON t1.tid != t2.id
group by id
所以你想谁是不存在的缺席用户?奇怪.... :) – barudo