Postgresql sql语句错误：column .. does not exist

我正在从postgres控制台try 此命令:

select sim.id as idsim, 
       num.id as idnum 
from main_sim sim 
  left join main_number num on (FK_Numbers_id=num.id);

我得到了这样的回应:

ERROR:  column "fk_numbers_id" does not exist
LINE 1: ...m from main_sim sim left join main_number num on (FK_Numbers...

用我的桌子判断一下，如果:

dbMobile=# \d main_sim

 id              | integer               | not null default

 Iccid           | character varying(19) | not null

...

 FK_Device_id    | integer               | 

 FK_Numbers_id   | integer               | 

Indexes:
    "main_sim_pkey" PRIMARY KEY, btree (id)
    "main_sim_FK_Numbers_id_key" UNIQUE, btree ("FK_Numbers_id")
    "main_sim_Iccid_key" UNIQUE, btree ("Iccid")
    "main_sim_FK_Device_id" btree ("FK_Device_id")
Foreign-key constraints:
    "FK_Device_id_refs_id_480a73d1" FOREIGN KEY ("FK_Device_id") REFERENCES main_device(id) DEFERRABLE INITIALLY DEFERRED
    "FK_Numbers_id_refs_id_380cb036" FOREIGN KEY ("FK_Numbers_id") REFERENCES main_number(id) DEFERRABLE INITIALLY DEFERRED

...正如我们所看到的，这个专栏是存在的.

可能是语法错误，但我看不出...

任何帮助都将不胜感激.