input: Write a function to convert a given SQL statement into a Python Pandas DataFrame. The function should take a string representing the SQL query and a database connection object as input, execute the query using pandas.read_sql_query(), and return the resulting DataFrame. If the query fails for any reason, the function should return an empty DataFrame.
  
  assert convert_sql_to_df("SELECT * FROM book;", conn).equals(pd.read_sql_query("SELECT * FROM book;", conn))
  assert convert_sql_to_df("SELECT title, author FROM book", conn).equals(pd.read_sql_query("SELECT title, author FROM book", conn))
  assert convert_sql_to_df("", conn).empty==True
  assert convert_sql_to_df("INVALID QUERY", conn).empty==True
output: def convert_sql_to_df(sql_query, conn):
      try:
          return pd.read_sql_query(sql_query, conn)
      except:
          return pd.DataFrame()