我有下面的表称为事务，我想使用列account_id添加外键。但是当我执行查询（见下文）时，0行受到影响。我没有得到查询的错误。
我有两个叫做交易和账户的表。帐户表具有id作为主键和帐户has_many事务。
交易表
+---------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| account_number | int(11) | YES | | NULL | |
| m_number | varchar(255) | YES | | NULL | |
| registration_number | varchar(255) | YES | | NULL | |
| page_number | varchar(255) | YES | | NULL | |
| entry_date | datetime | YES | | NULL | |
| narration | varchar(255) | YES | | NULL | |
| voucher_number | varchar(255) | YES | | NULL | |
| debit_credit | float | YES | | NULL | |
| profit | float | YES | | NULL | |
| account_code | int(11) | YES | | NULL | |
| balance | float | YES | | NULL | |
| branch | varchar(255) | YES | | NULL | |
| account_id | int(11) | YES | MUL | NULL | |
| created_at | datetime | YES | | NULL | |
| updated_at | datetime | YES | | NULL | |
+---------------------+--------------+------+-----+---------+----------------+
16 rows in set (0,01 sec)
mysql> ALTER TABLE transactions ADD FOREIGN KEY (account_id) REFERENCES accounts(id);
Query OK, 0 rows affected (0,03 sec)
Records: 0 Duplicates: 0 Warnings: 0
帐户表
+-----------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| account_number | int(11) | YES | | NULL | |
| account_code | int(11) | YES | | NULL | |
| branch | varchar(255) | YES | | NULL | |
| name | varchar(255) | YES | | NULL | |
| father_name | varchar(255) | YES | | NULL | |
| nic_number | varchar(255) | YES | | NULL | |
| mohalla | varchar(255) | YES | | NULL | |
| village | varchar(255) | YES | | NULL | |
| nominee | varchar(255) | YES | | NULL | |
| relationship | varchar(255) | YES | | NULL | |
| opening_balance | float | YES | | NULL | |
| opening_date | datetime | YES | | NULL | |
| created_at | datetime | YES | | NULL | |
| updated_at | datetime | YES | | NULL | |
+-----------------+--------------+------+-----+---------+----------------+
运行查询后，该列不应该说F_K或类似PRI吗？ 任何帮助都会很棒。谢谢！