Mysql 复制一个新表

1、复制表结构及数据到新表
CREATE TABLE 新表 SELECT * FROM 旧表
这种方法会将oldtable中所有的内容都拷贝过来，当然我们可以用delete from newtable;来删除。
不过这种方法的一个最不好的地方就是新表中没有了旧表的primary key、Extra（auto_increment）等属性。需要自己用"alter"添加，而且容易搞错。

2、只复制表结构到新表
CREATE TABLE 新表 SELECT * FROM 旧表 WHERE 1=2
或CREATE TABLE 新表  LIKE 旧表

这个和上面一样主键索引和一些属性都会消失。

原来的表：

MariaDB [syw]> desc news_person;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(30) | NO   |     | NULL    |                |
| age   | int(11)     | NO   |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
3 rows in set (0.05 sec)

执行后：

MariaDB [syw]> create table news_person_new select * from news_person where 1=2;
Query OK, 0 rows affected (0.49 sec)
Records: 0  Duplicates: 0  Warnings: 0

查看索引：

MariaDB [syw]> show index from news_person;
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table       | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| news_person |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set (0.00 sec)
 
MariaDB [syw]> show index from news_person_new;
Empty set (0.00 sec)

正确方法：

CREATE TABLE 新表
LIKE 旧表

MariaDB [syw]> create table news_person_new1 like news_person;
Query OK, 0 rows affected (0.24 sec)
 
MariaDB [syw]> desc news_person_new1;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(30) | NO   |     | NULL    |                |
| age   | int(11)     | NO   |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
3 rows in set (0.03 sec)
 
MariaDB [syw]> show index from news_person_new1;
+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table            | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| news_person_new1 |          0 | PRIMARY  |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set (0.00 sec)