Question

此查询将在找到该组织的摄像机后返回所有组织，否则将不返回一行。

SELECT org.id as organization_id, 
 cam.id as device_id,
 org.slug as organization_slug 
 FROM accounts_organization org 
 INNER JOIN devices_camera cam on org.id=cam.owner_id 
 WHERE org.slug IN ('org1','org2') and cam.unique_identifier = '123'

如何更改此设置，以便它将返回所有查询的组织，但是如果没有此类相关的摄像机，则该列字段将为空，但仍将显示该行？

Answer 1

将inner join更改为左联接，并将cam.unique_identifier = '123'更改为on子句

  SELECT org.id as organization_id, 
 cam.id as device_id,
 org.slug as organization_slug 
 FROM accounts_organization org 
 left JOIN devices_camera cam on org.id=cam.owner_id and  cam.unique_identifier = '123'
 WHERE org.slug IN ('org1','org2')

SQL查询返回列为空（如果找不到）

1 个答案: