PostgreSQL：外键约束中的列引用不存在

Question

我还是postgreSQL的新手。我有两个我创建的表，我想回去添加主键和外键约束，无论我做什么，我似乎无法添加外键。这就是我所拥有的：

两个表：

test=# \d statename
      Table "public.statename"
 Column |     Type      | Modifiers
--------+---------------+-----------
 code   | character(2)  | not null
 name   | character(30) |
Indexes:
    "statename_pkey" PRIMARY KEY, btree (code)

test=# \d customer
          Table "public.customer"   
    Column   |     Type      | Modifiers
-------------+---------------+-----------
 customer_id | integer       |
 name        | character(30) |
 telephone   | character(20) |
 city        | character(25) |
 street      | character(40) |
 state       | character(2)  |
 zipcode     | character(10) |
 country     | character(20) |

这是我正在运行的命令：

test=# ALTER TABLE customer ADD CONSTRAINT
state FOREIGN KEY (code) REFERENCES
statename (code) >MATCH FULL;

这是我得到的错误：

ERROR:  column "code" referenced in foreign key constraint does not exist

我正在看专栏！我知道它存在！请帮助一个兄弟！

Answer 1

客户表中不存在代码。这是州。

ALTER TABLE customer 
ADD CONSTRAINT state FOREIGN KEY (state) 
REFERENCES statename (code) >MATCH FULL;