从Mysql系统表中总结出来的建表规则

以下是系统表schema：information_schema的TABLES的建表语句

mysql> desc tables;

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

| Field |Type | Null | Key | Default |Extra |

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

| TABLE_CATALOG | varchar(512) | YES | | NULL | |

| TABLE_SCHEMA | varchar(64) | NO | | | |

| TABLE_NAME | varchar(64) | NO | | | |

| TABLE_TYPE | varchar(64) | NO | | | |

| ENGINE |varchar(64) | YES | |NULL | |

| VERSION |bigint(21) | YES | |NULL | |

| ROW_FORMAT | varchar(10) | YES | | NULL | |

| TABLE_ROWS | bigint(21) | YES | | NULL | |

| AVG_ROW_LENGTH | bigint(21) | YES | | NULL | |

| DATA_LENGTH | bigint(21) | YES | | NULL | |

| MAX_DATA_LENGTH | bigint(21) | YES | | NULL | |

| INDEX_LENGTH | bigint(21) | YES | | NULL | |

| DATA_FREE | bigint(21) |YES | | NULL | |

| AUTO_INCREMENT | bigint(21) | YES | | NULL | |

| CREATE_TIME | datetime |YES | | NULL | |

| UPDATE_TIME | datetime |YES | | NULL | |

| CHECK_TIME | datetime |YES | | NULL | |

| TABLE_COLLATION | varchar(64) | YES | |NULL | |

| CHECKSUM | bigint(21) |YES | | NULL | |

| CREATE_OPTIONS | varchar(255) | YES | |NULL | |

| TABLE_COMMENT | varchar(80) | NO | | | |

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

21 rows in set (0.00 sec)

有以下总结：

1：如果可能varchar用2的幂数，具体的最好是16的偶数倍。

2：CREATE_TIME 与UPDATE_TIME 用datetime型，除非必要不用timestamp，不用缺省值。

3：bigint用21位