条件PostgreSQL外键

类似于：ALTER TABLE table1 ADD FOREIGN KEY(some_id)REFERENCES other_table WHERE some_id NOT IN(0,-1)AND some_id IS NOT NULL;

具体来说,我的引用表具有所有正整数(1)但是我需要添加外键的表可以包含零(0),空和负一(-1),所有这些都意味着不同的东西.

笔记：

I am fully aware that this is poor table design,but it was a clever trick built 10+ years ago when the features and resources we have available at this point did not exist. This system is running hundreds of retail stores so going back and changing the method at this point could take months which we don’t have.

I can not use a trigger,this MUST be done with a foreign key.