Question

Not sure if this is the best structure for my database but this is what I have at the moment (open to suggestions for alterations). I basically want to create pages that have a user defined set of fields for each page. So I have four tables: pages, page_fields, page_data and data_fields.

pages:

id   name
 1   home

page_fields:

page_id field_id
   1       1
   1       2
   1       3

page_data:

 page_id  field_id  content
    1        1      'This is the Title'
    1        3      'Some description here'

data_fields:

id  field_name   field_type
1     title         text
2    subtitle       text
3   description    textarea

First of all is this a good database structure?
Secondly, how can I get the required fields as defined by the page_field table, the data (if there is any) for that field and the filed_name and filed_type given that we know the page id?

I presume there will be a couple of joins here but I just can’t work them out.

Any help appreciated.

Answer 1

1. Assuming that one field on one page can have single value, you can easily eliminate page_fields table. List of fields assigned to the page will be stored in page_data and if there is no content yet, NULL value will be in the content column.

2. Something like SELECT * FROM page_fields INNER JOIN page_data ON (page_fields.page_id = page_data.page_id) INNER JOIN data_fields ON (page_data.field_id = data_fields.id);

3. Additionally read about Entity Attribute Value model, may be it will generate some new ideas and generally useful for understanding things: http://en.wikipedia.org/wiki/Entity-attribute-value_model