create table like 和create table select 比较

语法:

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name

    [(create_definition,...)]

    [table_options] [select_statement]

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name

    [(] LIKE old_tbl_name [)];

测试过程:

原数据表:

mysql> show create table test_order \G
*************************** 1. row ***************************
       Table: test_order
Create Table: CREATE TABLE `test_order` (
  `pay_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `origin` int(10) DEFAULT NULL,
  `team_id` int(11) DEFAULT NULL,
  `state` int(11) DEFAULT NULL,
  KEY `team_id` (`team_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> create table cc select * from test_order;
Query OK, 9900 rows affected (0.11 sec)
Records: 9900  Duplicates: 0  Warnings: 0

mysql> create table dd like test_order;               
Query OK, 0 rows affected (0.22 sec)

查看数据:

mysql> select * from cc limit 2;
+---------------------+--------+---------+-------+
| pay_time            | origin | team_id | state |
+---------------------+--------+---------+-------+
| 2011-06-22 18:04:47 |     10 |     100 |   100 |
| 2011-06-22 18:04:47 |     10 |     100 |   101 |
+---------------------+--------+---------+-------+
2 rows in set (0.00 sec)

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

结果:cc表中数据与原表test_order中的一致，dd表中无数据

查看表结构:

mysql> show create table cc \G
*************************** 1. row ***************************
       Table: cc
Create Table: CREATE TABLE `cc` (
  `pay_time` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
  `origin` int(10) DEFAULT NULL,
  `team_id` int(11) DEFAULT NULL,
  `state` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> show create table dd \G
*************************** 1. row ***************************
       Table: dd
Create Table: CREATE TABLE `dd` (
  `pay_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `origin` int(10) DEFAULT NULL,
  `team_id` int(11) DEFAULT NULL,
  `state` int(11) DEFAULT NULL,
  KEY `team_id` (`team_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

结果：cc表中，原表中的索引消失了；dd表与原表一致

结论：

     create table select 会将原表中的数据完整复制一份，但表结构中的索引会丢失。

     create table like 只会完整复制原表的建表语句，但不会复制数据