'Check if this credential ID is valid.'

def is_credential_valid(self, credentialID):

    cur = self.conn.cursor()
    cur.execute('SELECT    *    FROM    users    WHERE    id=?    AND    password    IS    NOT    NULL    LIMIT    1', [credentialID])
    results = cur.fetchall()
    cur.close()
    return (len(results) > 0)
