如果选择两次，则无法在表上加入

Question

我正在尝试在MySQL中构建如下查询：

select
  t1.id
  ,t1Next.code as nextCode
  ,t1Prev.code as prevCode
from
  t1
  ,(select * from t2 where idMain in (idList)) as t2Main
  ,(select * from t2 where idAssoc in (idList)) as t2Assoc
inner join t1 as t1Next on t1Next.id = t2Main.idAssoc
inner join t1 as t1Prev on t1Prev.id = t2Assoc.idMain
where t1.id in (idList)
  and t2Main.idMain = t1.id
  and t2Assoc.idAssoc = t1.id

哪个返回错误Unknown column 't2Main.idAssoc' in 'on clause'。

此查询可行：

select
  t1.id
  ,t1Next.code as nextCode
from
  t1
  ,(select * from t2 where idMain in (idList)) as t2Main
inner join t1 as t1Next on t1Next.id = t2Main.idAssoc
where t1.id in (idList)
  and t2Main.idMain = t1.id

像这样添加第二个子查询，会中断查询并导致上述错误：

select
  t1.id
  ,t1Next.code as nextCode
from
  t1
  ,(select * from t2 where idMain in (idList)) as t2Main
  ,(select * from t2 where idAssoc in (idList)) as t2Assoc
inner join t1 as t1Next on t1Next.id = t2Main.idAssoc
where t1.id in (idList)
  and t2Main.idMain = t1.id

为什么会这样？