input: from typing import List
  
  def create_table_of_contents(db_data: List[str]) -> str:
      """Generate an HTML page that displays a table of contents from the data stored in a database.
      >>> create_table_of_contents(["Chapter 1", "Section 1.1", "Section 1.2", "Chapter 2", "Section 2.1"])
      "<html><body><ul><li>Chapter 1</li><ul><li>Section 1.1</li><li>Section 1.2</li></ul><li>Chapter 2</li><ul><li>Section 2.1</li></ul></ul></body></html>"
      """
output:     html_content = "<html><body><ul>"
      current_chapter = None
  
      for item in db_data:
          if item.startswith("Chapter"):
              if current_chapter is not None:
                  html_content += "</ul>"
              html_content += f"<li>{item}</li><ul>"
              current_chapter = item
          elif item.startswith("Section"):
              html_content += f"<li>{item}</li>"
  
      if current_chapter is not None:
          html_content += "</ul>"
  
      html_content += "</ul></body></html>"
      return html_content