Re: a problem about database modeling

Bob Badour wrote:

> Marshall wrote:
> > dxuranus wrote:
> >
> >>i have a entity 'device' and every 'device' has there own 'type' and
> >>every 'type' has there specific attributes.
> >>  first i let the table 'device' keep all common attributs of device
> >>,but i find i can't keep the 'device's type attributes at least i found
> >>if i do that.it got be urgly and strangly.
> >>so what can i do about this thanks for any help.
> >
> > Can you be more specific about the problem you are having?
> > I don't know how to help with urgliness and strangliness.
>
> Hit it with an urgly stick and if that doesn't kill it strangly it with
> a shoelace?

ok
i list my sql code here
table device:
CREATE TABLE `equ` (

`equ_id` varchar(32) NOT NULL default '',

`type_id` varchar(32) default NULL,

`equ_code` varchar(32) default NULL,

`equ_stat` varchar(32) default NULL, //device state

`equName` varchar(32) default NULL,

  PRIMARY KEY (`equ_id`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8

table device attributes:
CREATE TABLE `equpro` (

`equ_id` varchar(32) NOT NULL default '',

`tp_id` varchar(32) NOT NULL default '', //device type attribute
id

`value` varchar(32) default NULL, //the value of
device type attribute
  PRIMARY KEY (`equ_id`,`tp_id`),

  KEY `equpro_FK` (`equ_id`),

  KEY `equpro2_FK` (`tp_id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8

table device type:
CREATE TABLE `type` (

`type_id` varchar(32) NOT NULL default '',

`type_name` varchar(32) default NULL,

`type_father` varchar(32) default NULL,//the type's father(also a
type)
 id
  PRIMARY KEY (`type_id`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8

table device type attributes
 CREATE TABLE `typepro` (

`tp_id` varchar(32) NOT NULL default '',

`type_id` varchar(32) default NULL,

`tp_name` varchar(32) default NULL,

`tp_code` varchar(32) default NULL,

`tp_note` varchar(32) default NULL,

`tp_others` varchar(32) default NULL,

`tp_null` tinyint(1) default NULL,

  PRIMARY KEY (`tp_id`),

) ENGINE=MyISAM DEFAULT CHARSET=utf8

thanks for any help! Received on Thu Jul 20 2006 - 11:07:43 CEST