MySQL中兩種快速創建空表的方式的區別

在MySQL中有兩種方法 1、create table t_name select ... 2、create table t_name like ... 第一種會取消掉原來表的有些定義，且引擎是系統默認引擎。 手冊上是這麽講的：Some conversion of data types might occur. For example, the AUTO_INCREMENT attribute is not preserved, and VARCHAR columns can become CHAR columns. 第二種就完全複制原表。 先建立測試表: 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) 第一種方式： 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) 第二種方式： 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>