docs: def sql(self, input_string, *args):
          """Execute a SQL command using the Python DBI directly.
  
          Connection parameters are taken from self.  Autocommit is in effect.
  
          Example: .sql('SELECT %s FROM %s WHERE age > %s', 'name', 'table1',
              '45')
  
          @param input_string: A string of SQL.  May contain %s or %(name)s
          format specifiers; they are replaced with corresponding values taken
          from args.
  
          @param args: zero or more parameters to interpolate into the string.
          Note that they're passed individually, not as a single tuple.
  
          @return: Whatever .fetchall() returns.
          """
          """
          # I advise against using sqlalchemy here (it's more complicated than
          # what we need), but here's an implementation Just In Case.  -jps
          import psycopg2, sqlalchemy
          engine = sqlalchemy.create_engine(
              'postgres://%s@%s:%s/%s' %
              (self.user, self.host, self.port, self.db_name),
              echo=False, poolclass=sqlalchemy.pool.NullPool)
          connection = engine.connect()
          result = connection.execute(input_string, *args)
          try:
              # sqlalchemy 0.6.7 offers a result.returns_rows attribute, but
              # no prior version offers anything comparable.  A tacky
              # workaround...
              try:
                  return result.fetchall()
              except psycopg2.ProgrammingError:
                  return None
          finally:
              result.close()
              connection.close()
          """
          psycopg2 = importlib.import_module('psycopg2')
          importlib.import_module('psycopg2.extensions')
          connection = psycopg2.connect(
              user=self.user, host=self.host,
              port=self.port, database=self.db_name)
          connection.set_isolation_level(
              psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)
          try:
              cursor = connection.cursor()
              cursor.execute(input_string, args)
              # No way to ask whether any rows were returned, so just try it...
              try:
                  return cursor.fetchall()
              except psycopg2.ProgrammingError:
                  return None
          finally:
              connection.close()