+------------+           +--------------------------+           +-----------------------+
| product    |           | product_attribute        |           |product_attribute_key  |
+------------+           +--------------------------+           +-----------------------+
|id          | <--1:1--o |product_id                |     +---> |id                     |
|price       |           |product_attribute_key_id  | o---+     |name                   |
|quantity    |           |product_attribute_value_id| o---+     +-----------------------+
|...         |           +--------------------------+     |     +-----------------------+
|category_id |                                           1:n    |product_attribute_value|
+------------+                                            |     +-----------------------+
                                                          +---> |id                     |
                                                                |name                   |
                                                                +-----------------------+
		
		

product attribute group

		
+------------+           +--------------------------+           +--------------------------+           +-----------------------+
| category   |           | product_attribute_group  |           | product_attribute        |           |product_attribute_key  |
+------------+           +--------------------------+           +--------------------------+           +-----------------------+
|id          |     +---> |id                        | <--1:n--o |product_attribute_group_id|     +---> |id                     |
|title       |     |     |name                      |           |product_attribute_key_id  | o---+     |name                   |
|description |    1:1    |status                    |           |product_attribute_value_id| o---+     +-----------------------+
|status      |     |     +--------------------------+           +--------------------------+     |     +-----------------------+
|parent_id   |     |                                                                            1:n    |product_attribute_value|
|default_pag | o---+                                                                             |     +-----------------------+
+------------+                                                                                   +---> |id                     |
                                                                                                       |name                   |
                                                                                                       +-----------------------+
		
		

product attribute group

		    
    +------------+           +------------------+           +--------------------------+           +---------------------------------+
    | category   |           | attribute_group  |           | group_has_attribute      |           |attribute_key                    |
    +------------+           +------------------+           +--------------------------+           +---------------------------------+
 +->|id          |     +-->  |id                | <--1:n--o |attribute_group_id        |     +-+-> |id                               |
 |  |title       |     |     |name              |           |attribute_key_id          | o---+ |   |name                             |
 |  |description |    1:1    |status            |           |                          |       |   |type enum('Bool','List','Input') |
 |  |status      |     |     +------------------+           +--------------------------+       |   |default array()                  |
 |  |parent_id   |     |                                                                       |   +---------------------------------+
 |  |default_pag | o---+                                                                       |
 |  +------------+                                                                             |
1:n                                                                                            |
 |  +-------------+             +--------------------------+                                   |
 |  | product     |             | product_attribute        |                                   |
 |  +-------------+             +--------------------------+                                   |
 |  |id           |         +-> |product_id                |                                   |
 |  |price        |         |   |attribute_key_id          | o---------------1:n---------------+
 |  |quantity     |         |   |attribute_value           |
 |  |...          |         |   +--------------------------+
 +-o|category_id  |         |
    |attr_group_id| <--1:n--o
    +-------------+
		    
		    

+--------------------------------------------------+
| product_attribute_key                            |
+--------------------------------------------------+
| 1 | color | list | red,green,blue                |
| 2 | sex   | bool | Female,Male                   |
| 3 | qty   | input| ''                            |
+--------------------------------------------------+