No, they are not polyhierarchical. The main idea is that a subcategory is linked to only one main category so the category is listed as the head then it’s children listed below it separated by commas.
What is the advantage/disadvantage of this method (ie 1 db table) vs having a table of Categories and a SubCategories table…
I normally use 2 table -eg Links and Link Types - I select the link details (url etc) and also the title of the link type and order by the link type…Then loop through all results only echoing the Link type heading if the link type is different to the last row that was processed…
think of a situation when you dont know how many sub category are there. if you want to leave the control in the hands of administrator, when administrator can add categories, subcategories, its difficult to create a table each time specially when you r creating a subcategory under a subcategory.
i hope this explains, or you can question if u want something else.
Jito - thanks for that - originally i thought that you meant the number of subcategories, but in fact you are actually referring to the levels in the hierarchy - categories, subcategories, sub-subcategories etc.
I understand - thanks again.
I will take a look at the article suggested by wysiwyg now.