[customer] 写错了，该写bossone
求 User10 User20 User30 User60 的所有上级
select a.id,a.[User] ,a.customer as bossone,bosstwo = b.[customer]
,bossthree = c.customer from tem a
left join tem b on a.customer = b.[user]
left join tem c on b.customer = c.[user]
where a.[User] = 'user10' or a.[User] = 'user20' or a.[User] = 'user30' or a.[User] = 'user60'