sql - SQLの左結合と右結合.

Question

SQL で 3 つのテーブルを結合しようとしています。次のクエリを使用していますが、機能していません

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

誰でも助けることができますか？

Answer 1

セミコロンを追加し、単一の等号を使用します。

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;