Sql 选择具有某些值但同时没有其他值的记录

在开始之前，感谢您的帮助

我的问题是：我有一个表，例如activity_records，它有一个日期列和一个activity_id列

我只想选择那些日期，例如，在具有相同日期的任何其他记录中，activity_id值为1但不具有2的日期

我尝试过多选查询和所有这些

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

另请参见不存在的地方，并应用于更复杂的场景。

一种方法使用不存在：

因为您只需要日期，所以另一种选择是分组方式：

或者，最简单的是针对这种特殊情况：

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

---

另一种方法是只对具有一个不同activity_id的日期进行筛选，然后通过自联接过滤那些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;

---

一种方法不适用于：

---

从活动\记录中选择ar.*，其中ar.activity\ id=1，ar.date不在活动\记录中选择ar2.date，其中ar2.activity\ id=2

谢谢！这些解决方案太棒了，我要全部尝试！

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

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;