How should i get corresponding field value for taxonomy filed attached?

Question

I use drupal 7. I created a content type with these fields:

1. one field to upload a file to private folder
2. a taxonomy field (for that file)

my problem: i can save one file with one taxonomy! but how should i get these data again!(is there any API here) I want to know which taxonomy was saved for a certain file(i need to check it inside my custom module). i raised similar question here: so by following code i can get corresponding field:

$nids = db_query("SELECT nid FROM node WHERE title LIKE :title", array(':title' => '%'.$title.'%'))->fetchCol();

$nodes = node_load_multiple($nids);

foreach($nodes as $node) {

// using field_get_items here automatically loads the field in the correct language
$field_items = field_get_items('node', $node, 'field_subtitle');
$subtitle = $field_items[0]['safe_value'];
}

but it seems it dose not work taxonomy attached field.

why do i have this question: i sell some digital files and now i am developing a module for selling my files. i want to sell them this way: each file has a certain taxonomy. when my user buys that file he or she gets that taxonomy(and i will keep it in one table). once he clicks on download link i have to check whether that user has that taxonomy already or not! if he has i will let him to download it.

Answer 1

You can see the relationship by viewing or editing the node.

If you mean where is this data stored in the DB then if you created a field called file_type then the tid of the associated taxonomy term would be found in the field_data_field_file_type table.

The names of the taxonomy terms are stored in the taxonomy_term_data table.