The difference between two quick ways to create empty tables in MySQL

There are two ways to do this in MySQL

1, CREATE TABLE T_name Select ...

2, CREATE table t_name like ...

The first one cancels out some definitions of the original table, and the engine is the system default engine.

This is what the manual says: Some Conversion of data types might occur. For example, the auto_increment are not preserved, and VARchar columns can become char columns.

The second is a complete copy of the original table.

First set up the test table:

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)

The first way:

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)

The second way:

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>