drupal custom query/coding

Hello, I have a Drupal issue that I need help with. I have a project that was coded by someone else on Drupal 7 but apparently does not follow any of drupal's standards and was coded like a website with overwriting the template system (and it is too late to modify or edit any of the current structure) I have the following issue to which I need to build a custom query: The data in the CMS is created as such: category (created in taxonomy) -> subcategory (created as a content type) -> item (created as a content type) When adding the entries in the CMS, the workflow is as such: first you create the main category from taxonomy (named Category) the you create the subcategory from the contents when adding/editing the subcategory, you select the parent Category from a radio list and the items are selected from a checkbox list I have taken screenshots from the CMS so help make things clearer regarding the structure, they can be found here: [login to view URL] The problem is that I am not being able to build the view for this at all, I would need to create a custom query that can do the following: read the Categories Read the Subcategories belonging to each category read the items under each category with php, generate a custom html using loops on the above data The purpose of this is so that on the website, user to be able to click a category, and to get a list of subcategories. When the subcategory is clicked, the items in it can be seen. In typical php/mysql, the query process would look like this (assuming no joins): <?php $categories = query('SELECT * FROM categories'); while ($category = fetcharray($catetgories)) { $subcategories = query('SELECT * FROM subcategories WHERE category = $category['id']); while ($subcategory = fetcharray($subcategories)) { $items = query('SELECT * FROM items WHERE subcategory = $subcategory['id']); } } ?> I need to be able to replicate the above by doing a query to get items of taxonomy "Category", find subcategories (content type) that belong to it, and then find items that belong to the subcategory I need this completed by Sunday 8pm GMT thank you all PS: anyone bidding, please make it clear that you actually read the above (will not accept any automated bids) Also, you must be highly professional in Drupal, at least several years experience, so do mention your knowledge please