这个本身属于MySQL的基本语法，我这里给出一个例子而已。
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mysql> -- 测试数据库在指定位置增加字段
mysql> drop table if exists t;
Query OK, 0 rows affected (0.06 sec)
mysql> create table t(age int,address varchar(50));
Query OK, 0 rows affected (0.06 sec)
mysql> desc t;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| age | int(11) | YES | | NULL | |
| address | varchar(50) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
2 rows in set (0.02 sec)
mysql> alter table t add column name varchar(20) after age;
Query OK, 0 rows affected (0.16 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc t;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| age | int(11) | YES | | NULL | |
| name | varchar(20) | YES | | NULL | |
| address | varchar(50) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql> alter table t add column id int FIRST;
Query OK, 0 rows affected (0.13 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc t;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| age | int(11) | YES | | NULL | |
| name | varchar(20) | YES | | NULL | |
| address | varchar(50) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
mysql>
mysql> -- 测试数据库在指定位置增加字段
mysql> drop table if exists t;
Query OK, 0 rows affected (0.06 sec)
mysql> create table t(age int,address varchar(50));
Query OK, 0 rows affected (0.06 sec)
mysql> desc t;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| age | int(11) | YES | | NULL | |
| address | varchar(50) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
2 rows in set (0.02 sec)
mysql> alter table t add column name varchar(20) after age;
Query OK, 0 rows affected (0.16 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc t;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| age | int(11) | YES | | NULL | |
|姓名 | varchar(20) | varchar(20)是的 | |空 | |
|地址 | varchar(50) | varchar(50) |是的 | |空 | |
--------- ------------- ------ ----- --------- ---- ---
集合中的 3 行（0.00 秒）
mysql> alter table t add column id int FIRST;
查询正常，0 行受影响（0.13 秒）
记录：0 重复：0 警告：0
mysql>; desc t;
--------- ------------- ------ ----- --------- -- -----
|领域 |类型 |空 |关键|默认 |额外 |
--------- ------------- ------ ----- --------- --- ----
| id |整数（11） |是的 | |空 | |
|年龄 |整数（11） |是的 | |空 | |
|姓名 | varchar(20) | varchar(20)是的 | |空 | |
|地址 | varchar(50) | varchar(50) |是的 | |空 | |
--------- ------------- ------ ----- --------- ---- ---
集合中的 4 行（0.00 秒）
mysql>
相关语法描述为
更改 [在线 |离线] [忽略] 表 tbl_name alter_specation [, alter_specation] ...alter_specation: table_option ... |添加 [列] col_name column_definition [第一 |在 col_name 之后]
