def mk_update(db, table, changes=None, cond=None):

    '''

    @param changes [(col, new_value),...]

        * container can be any iterable type

        * col: sql_gen.Code|str (for col name)

        * new_value: sql_gen.Code|literal value

    @param cond sql_gen.Code WHERE condition. e.g. use sql_gen.*Cond objects.

    @return str query

    '''

    query = 'UPDATE '+sql_gen.as_Table(table).to_str(db)+'\nSET\n'

    query += ',\n'.join((sql_gen.to_name_only_col(col).to_str(db)+' = '

        +sql_gen.as_Value(new_value).to_str(db) for col, new_value in changes))

    if cond != None: query += ' WHERE '+cond.to_str(db)

    return query

def update(db, *args, **kw_args):

    '''For params, see mk_update() and run_query()'''

    recover = kw_args.pop('recover', None)

    return run_query(db, mk_update(db, *args, **kw_args), [], recover)