Question

开始之前，谢谢你的帮助。

我的问题是：我有一个表格，例如activity_records，其中包含date列和activity_id列。

我只想选择那些日期，例如activity_id值为1但在任何其他记录中都没有2的日期日期。

我尝试了多选查询等等。

Answer 1

一种方法使用not exists：

select ar.*
from activity_records ar
where ar.activity_id = 1 and
      not exists (select 1
                  from activity_records ar2
                  where r2.date = ar.date and ar2.activity_id = 2
                 );

因为您只想要日期，所以选择group by：

select ar.date
from activity_records ar
group by ar.date
having sum(case when ar.activity_id = 1 then 1 else 0 end) > 0 and
       sum(case when ar.activity_id = 2 then 1 else 0 end) = 0;

或者，最简单的就是这个特例：

select ar.date
from activity_records ar
where ar.activity_id in (1, 2)
group by ar.date
having max(ar.activity_id) = 1 ;

Answer 2

SELECT [date] FROM [activity_records] WHERE [activity_id] = 1
EXCEPT
SELECT [date] FROM [activity_records] WHERE [activity_id] = 2

有关更复杂的方案，另请参阅WHERE NOT EXISTS和APPLY。

Answer 3

另一种方法是仅使用一个不同activity_id的日期，然后通过自我加入过滤activity_id = 1的日期。

SELECT DISTINCT B.DATE
FROM
(SELECT DATE, COUNT(DISTINCT ACTIVITY) AS COUNT_ACTIVITIES
FROM YOUR_TABLE
GROUP BY DATE
HAVING COUNT(DISTINCT ACTIVITY) = 1) A
INNER JOIN
YOUR_TABLE B
ON A.DATE = B.DATE
AND B.ACTIVITY_ID = 1;

Answer 4

一种不使用的方法：

从activity_records ar中选择ar。*，其中ar.activity_id = 1且ar.date不在（从activity_records ar2中选择ar2.date，其中ar2.activity_id = 2）;

选择具有某些值但同时没有其他值的记录

4 个答案: