SQL联接与不存在
SQL联接与不存在
提问于 2022-05-27 18:21:26
comms
+-------------+
| uuid |
+-------------+
| comm_uuid_1 |
| comm_uuid_2 |
+-------------+
events
+--------------+-------------+
| uuid | comm_uuid |
+--------------+-------------+
| event_uuid_1 | comm_uuid_1 |
| event_uuid_2 | comm_uuid_1 |
+--------------+-------------+
actions
+---------------+-------+---------------------+
| uuid | type | event_uuid |
+---------------+-------+---------------------+
| random_uuid_1 | stack | event_uuid_1 |
| random_uuid_2 | pop | event_uuid_1 |
+---------------+-------+---------------------+基本上，我试图获得它们的事件符合某些条件的所有通信，但是过滤器在事件的操作中，这是我使用的查询：
SELECT *
FROM comms JOIN events ON events.comm_uuid = comms.uuid
AND (EXISTS (SELECT 1 FROM actions
WHERE events.uuid = actions.event_uuid AND actions.type = 'stack'))
AND (not EXISTS (SELECT 1 FROM actions
WHERE events.uuid = actions.event_uuid AND actions.type = 'pop')) 在本例中，该查询不应该返回任何内容，因为存在actions.type =堆栈的事件，但在与actions.type = pop相同的通信中也存在事件，由于某种原因，这将返回与action.type =堆栈相关的通信，我只希望在同一通信方式的事件中没有action.type = pop。
回答 1
Stack Overflow用户
发布于 2022-05-27 22:35:40
SELECT * FROM comms
WHERE
EXISTS (
SELECT 1 FROM actions
JOIN events on (events.uuid = actions.event_uuid)
WHERE events.comm_uuid = comms.uuid
AND actions.type = 'stack')
AND NOT EXISTS (
SELECT 1 FROM actions
JOIN events on (events.uuid = actions.event_uuid)
WHERE events.comm_uuid = comms.uuid
AND actions.type = 'pop'
)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/72409614
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