如何检索包含和排除特定键的列表？

Question

我有一个像这样的 table，我需要过滤键并检索键列表。

期望的输出：

这里我想获取一个 ID 列表，即 (2,3)，其中存在键 1 而缺少键 2。

Answer 1

这回答了问题 "Here i want to get a list of id . . . in which key 1 is present and key 2 is missing."

您可以使用 exists 和 not exists:

select t.*
from t
where exists (select 1 from t t2 where t2.id = t.id and t2.key = 1) and
      not exists (select 1 from t t2 where t2.id = t.id and t2.key = 2);

如果你只想要id，那么我更喜欢聚合和having:

select id
from t
group by id
having sum(case when key = 1 then 1 else 0 end) > 0 and
       sum(case when key = 2 then 1 else 0 end) = 0;

Answer 2

假设您的 table 名称是 'testing' 那么根据您提到的输出，sql 查询将是

SELECT * 来自 testing WHERE key !=2 and id in (2,3)

如何检索包含和排除特定键的列表？

how to retrieve a list including and excluding a particular key?

sql

teradata