Drupal/schema

The basic unit of content in Drupal is the node, which is represented by the nodes table. Key data concepts are:

• content type
• node
• node type
• tag
• taxonomy
  • taxonomy term - hierarchical - home table is taxonomy_term_data
  • taxonomy vocabulary - home table is taxonomy_vocabulary

Things you may encounter that aren't actually data concepts:

• category: it is common to have a taxonomy_vocabulary record called "category" or "categories".

Rules

• Any node can be assigned to zero or more taxonomy terms. (taxonomy_index)
• Any taxonomy term can be assigned to zero or more nodes. (taxonomy_index)
• Each taxonomy term is assigned to exactly one taxonomy vocabulary. (taxonomy_term_data)
• Each taxonomy term has zero or one parent and zero or more children. (taxonomy_term_hierarchy)