Question

select distinct scene.title,staff.job_descr
from actor
inner join scene
on scene.id=actor.id_scene 
left join staff
on scene.id=staff.Ids

这段代码将所有（电影）场景归还给我工作的工作人员。有些场景没有工作人员在工作，我怎么才能只显示那些场景？

Tile            job_descr 
First murder    makeup artist 
First scene     NULL
Guest singer    NULL 
Haunt scene 5   janitor    
New year concert    management

例如，上面是我收到的结果的一部分，我想只显示第二行和第三行。

Answer 1

只需在where子句中添加条件，如下所示

SELECT DISTINCT scene.title, 
                staff.job_descr 
FROM   actor 
       INNER JOIN scene 
               ON scene.id = actor.id_scene 
       LEFT JOIN staff 
              ON scene.id = staff.ids 
WHERE  staff.job_descr IS NULL

使用连接和空列进行查询

1 个答案: