第一种是通过not in的方式去处理：
select id from table_a where id not in (select id from table_b);
第二种则是通过左连接(left join)的方式：
select * from table_a as a
left join table_b as b
on a.id = b.id
where a.id is NULL;
取AB表的差集，就是拿A表独有数据跟B表独有数据合并
那么思路就有了，直接通过union将两个查询的结果合并即可。
select * from A left join B on A.id = B.id where B.id is null
union
select * from A right join B on A.id = B.id where A.id is null;
同一个订单存在多条记录，需要过滤出失败的记录。就a集合中的失败的，与a集合中成功的差集
代码语言：javascript复制select DISTINCT order_no from (
SELECT order_no
FROM order_mqmsg
WHERE notify_status != 1 and date( `create_time`) >= '2022-05-01' and date( `create_time`) <= '2022-05-31'
GROUP BY `order_no`
) t1 WHERE t1.`order_no` not in (
select DISTINCT order_no from (
SELECT order_no
FROM order_mqmsg
WHERE notify_status = 1 and date( `create_time`) >= '2022-05-01' and date( `create_time`) <= '2022-05-31'
GROUP BY `order_no`
) t2
)
