ORA-01791: 不是 SELECTed 表达式

select distinct fr.name fname from tms_shipment_carrying_detail t
left join tms_shipment s on s.id=t.shipment_id
left join tms_legs f_leg on f_leg.shipment_id=s.id
left join tms_trans_location tr on tr.id=f_leg.tolocation_id
left join tms_trans_location fr on fr.id=f_leg.fromlocation_id
order by tr.name;
ORA-01791: 不是 SELECTed 表达式！
原因：select distinct 和order by一起使用的时候，order by中必须是常量或者select列表中出现的表达式。（单表时没有这种情况）
改为：
select distinct fr.name fname,tr.name tname from tms_shipment_carrying_detail t
left join tms_shipment s on s.id=t.shipment_id
left join tms_legs f_leg on f_leg.shipment_id=s.id
left join tms_trans_location tr on tr.id=f_leg.tolocation_id
left join tms_trans_location fr on fr.id=f_leg.fromlocation_id
order by tr.name ;