mysql актуализира колона с int въз основа на реда

SET @rownumber = 0;    
update mytable set Moneyorder = (@rownumber:[email protected]+1)
order by MoneyOrder asc

или да го направите с една заявка, можете да опитате

update mytable target
join
(
     select id, (@rownumber := @rownumber + 1) as rownum
     from mytable         
     cross join (select @rownumber := 0) r
     order by MoneyOrder asc
) source on target.id = source.id    
set Moneyorder = rownum