@classmethod
def copy(cls, conn, **where):
    """Copy data from one table to another while filtering data at the same time

        Parameters
        ----------
        conn: sqlite3 DB connection.  It must have a second database
            attached as "other".
        **where : keyword arguments
            specifying (start_ut and end_ut for filtering, see the copy_where clause in the subclasses)
        """
    cur = conn.cursor()
    if where and cls.copy_where:
        copy_where = cls.copy_where.format(**where)
    else:
        copy_where = ''
    cur.execute('INSERT INTO %s SELECT * FROM source.%s %s' % (cls.table,
        cls.table, copy_where))
