您现在的位置:软界网技术中心数据库MySQL > 技术显示
MySQL中两种快速创建空表的方式的区别
2008-6-10 0:00:00   网友评论       阅读次数 点此评论
   

  MySQL中有两种方法

  1、create table t_name select ...

  2、create table t_name like ...

  第一种会取消掉原来表的有些定义,且引擎是系统默认引擎。

  手册上是这么讲的:Some conversion of data types might occur. For example, the AUTO_INCREMENT attribute is not preserved, and VARCHAR columns can become CHAR columns.

  第二种就完全复制原表。

  先建立测试表:

  mysql> create database dbtest;

  Query OK, 1 row affected (0.03 sec)

  mysql> use dbtest;

  Database changed

  mysql> create table t_old

  -> (

  -> id serial,

  -> content varchar(8000) not null,

  -> `desc` varchar(100) not null)

  -> engine innodb;

  Query OK, 0 rows affected (0.04 sec)

  mysql> show create table t_old;

  +-------+-------------------------------------------------+

  | Table | Create Table |

  +-------+------------------------------------------------+

  | t_old | CREATE TABLE `t_old` (

  `id` bigint(20) unsigned NOT NULL auto_increment,

  `content` varchar(8000) NOT NULL,

  `desc` varchar(100) NOT NULL,

  UNIQUE KEY `id` (`id`)

  ) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

  +-------+----------------------------------------------------+

  1 row in set (0.00 sec)

  第一种方式:

  mysql> create table t_select select * from t_old where 1 = 0;

  Query OK, 0 rows affected (0.04 sec)

  Records: 0 Duplicates: 0 Warnings: 0

  mysql> show create table t_select;

  +----------+--------------------------------------------+

  | Table | Create Table +----------+---------------------------------------------+

  | t_select | CREATE TABLE `t_select` (

  `id` bigint(20) unsigned NOT NULL default '0',

  `content` varchar(8000) NOT NULL,

  `desc` varchar(100) NOT NULL

  ) ENGINE=MyISAM DEFAULT CHARSET=latin1 |

  +----------+-------------------------------------------+

  1 row in set (0.00 sec)

  第二种方式:

  mysql> create table t_like like t_old;

  Query OK, 0 rows affected (0.02 sec)

  mysql> show create table t_like;

  +--------+-------------------------------------------------+

  | Table | Create Table |

  +--------+-------------------------------------------------+

  | t_like | CREATE TABLE `t_like` (

  `id` bigint(20) unsigned NOT NULL auto_increment,

  `content` varchar(8000) NOT NULL,

  `desc` varchar(100) NOT NULL,

  UNIQUE KEY `id` (`id`)

  ) ENGINE=InnoDB DEFAULT CHARSET=latin1 |

  +--------+-------------------------------------------------+

  1 row in set (0.00 sec)

  mysql>

  

 
      来源: 作者:
 
【评论查看】