MySQL数据库在指定位置增加字段

 

这个本身属于MySQL的基本语法，我这里给出一个例子而已。

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: 0mysql> 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: 0mysql> 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>

 

相关的语法描述为

ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name
    alter_specification [, alter_specification] ...

alter_specification:
    table_option ...
  | ADD [COLUMN] col_name column_definition
        [FIRST | AFTER col_name ]