MySQL复制表-CREATE SELECT

假设存在以下Table：

mysql> select * from staff;
+----+----------+-------+
| id | name     | slary |
+----+----------+-------+
|  3 | haofugui | 10000 |
|  4 | guoming  |  3500 |
|  5 | haotian  |  2900 |
+----+----------+-------+
3 rows in set (0.00 sec)

mysql> describe staff;
+-------+----------+------+-----+---------+----------------+
| Field | Type     | Null | Key | Default | Extra          |
+-------+----------+------+-----+---------+----------------+
| id    | int(11)  | NO   | PRI | NULL    | auto_increment |
| name  | char(20) | YES  |     | NULL    |                |
| slary | int(11)  | YES  |     | NULL    |                |
+-------+----------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

1. 只复制表结构到新表

语句1：CREATE TABLE new_table_name SELECT [field1,field2... | *] FROM old_table_name WHERE 1=2;

语句2：CREATE TABLE new_table _name LIKE old_table_name;

示例：

mysql> create table staff_bak select id,name from staff where 1=2; //根据旧表的指定属性创建一个新的空表
Query OK, 0 rows affected (0.03 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> select * from staff_bak;   //新建的数据库为空表
Empty set (0.00 sec)

mysql> describe staff_bak;       //原表的主键和自动增长不能被复制
+-------+----------+------+-----+---------+-------+
| Field | Type     | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id    | int(11)  | NO   |     | 0       |       |
| name  | char(20) | YES  |     | NULL    |       |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> create table staff_bak_1 like staff;  //根据旧表创建一个新的空表，无法指定属性或属性组
Query OK, 0 rows affected (0.03 sec)

mysql> select * from staff_bak_1;
Empty set (0.00 sec)

mysql> describe staff_bak_1;    //所有数据类型和完整性约束条件都能被复制，包括主键和自动增长
+-------+----------+------+-----+---------+----------------+
| Field | Type     | Null | Key | Default | Extra          |
+-------+----------+------+-----+---------+----------------+
| id    | int(11)  | NO   | PRI | NULL    | auto_increment |
| name  | char(20) | YES  |     | NULL    |                |
| slary | int(11)  | YES  |     | NULL    |                |
+-------+----------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

注意：语句1可指定复制的属性范围，但无法复制主键类型和自增方式；

          语句2会把旧表的所有字段类型都复制到新表，但无法复制指定属性或属性组。

2. 复制表结构及数据到新表

语句：CREATE TABLE new_table_name SELECT [field1,field2... | *] FROM old_table_name;

mysql> create table staff_bak select id,name from staff;  //根据旧表将指定属性及其数据创建新表
Query OK, 3 rows affected (0.03 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> describe staff_bak;    //新表结构展示
+-------+----------+------+-----+---------+-------+
| Field | Type     | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id    | int(11)  | NO   |     | 0       |       |
| name  | char(20) | YES  |     | NULL    |       |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> select * from staff_bak;  //新表数据显示
+----+----------+
| id | name     |
+----+----------+
|  3 | haofugui |
|  4 | guoming  |
|  5 | haotian  |
+----+----------+
3 rows in set (0.00 sec)