sql中的左右连接

Question

我试图在SQL中连接三个表。 我使用下面的查询，但它不工作

select * 
from char_level as c1 right join (SELECT distinct character_id as fid, target_character_dbid as tid FROM house 
where reason='set_house_access' or reason='remove_house_access' and character_id is not null and target_character_dbid is not null)as vd on c1.character_id==vd.fid left join char_level as c2 on c2.character_id==vd.tid 

谁能帮助？

Answer 1

添加分号并使用单个等号。

select * 
from char_level c1 
right join 
(SELECT distinct character_id as fid, target_character_dbid as tid 
FROM house 
where (reason = 'set_house_access' 
or reason = 'remove_house_access') 
and character_id is not null 
and target_character_dbid is not null) vd 
on c1.character_id = vd.fid 
left join char_level c2 
on c2.character_id = vd.tid;