DELIMITER $$
DROP PROCEDURE IF EXISTS spNullifyRedundancy$$
CREATE PROCEDURE spNullifyRedundancy()
BEGIN

SET SQL_SAFE_UPDATES = 0;

drop temporary table if exists t;
create temporary table if not exists t as (
	SELECT column_name, @rnk := @rnk + 1 as rnk
	FROM INFORMATION_SCHEMA.COLUMNS as i, (select @rnk := 0) as v
	WHERE TABLE_SCHEMA = '..db...' AND TABLE_NAME = '...tbl...' and is_nullable = 'yes'
);
set @i = (select count(*) from t);

while @i > 0 do
	set @c = (select t.column_name from t where t.rnk = @i);
    set @prevVal = '';
	set @q = replace('
		update ...tbl... as l
			join (
				select id, r
                                from (
					SELECT id ,@prevVal != @c as r ,@prevVal := @c as v
					FROM ...tbl... as l, (select @prevVal := null) as v
					where @c is not null
					order by l.id
					) as t
				where r = 0
				) as t on l.id = t.id
		set @c = null
		', '@c', @c);
	prepare s from @q;
	execute s;
	deallocate prepare s;
    set @i = @i - 1;
end while;

end$$
DELIMITER ;