mysql update line according to data from next line - mysql

Question

I have this table in mysql:
name ID
B1 1
B2 1
B3 1
B4 2
B5 2
B6 2
A1 3
A2 3
A3 3
I'd like to add data into a column, notifying that the id will change at the next line. Something like this:
name beforeChange ID
B1 NO 1
B2 NO 1
B3 YES 1
B4 NO 2
B5 NO 2
B6 YES 2
A1 NO 3
A2 NO 3
A3 NO 3
A4 NO 3
Is there any way to do this in sql?
Thanks!

Answer 1

Ugly as sin & probably far from ideal from an efficiency point of view but seems to work:
create table myTable (id int(10) unsigned not null,name varchar(10));
insert into myTable (id,name) values (1,'B1');
insert into myTable (id,name) values (1,'B2');
insert into myTable (id,name) values (1,'B3');
insert into myTable (id,name) values (2,'B4');
insert into myTable (id,name) values (2,'B5');
insert into myTable (id,name) values (2,'B6');
insert into myTable (id,name) values (3,'A1');
insert into myTable (id,name) values (3,'A2');
insert into myTable (id,name) values (3,'A3');
insert into myTable (id,name) values (3,'A4');
select a.id,
case
when b.id is null then 'NO'
when b.id = (select max(id) from myTable) then 'NO' -- < handle last line of results set
else 'YES' end as beforeChange,a.name
from
-- rank within id
(
select mt.id,mt.name,
case mt.id when #curId then #curRow := #curRow + 1
else #curRow := 1 and #curId := mt.id END as rank
from myTable mt
join (select #curRow := 0, #curId := -1) r
order by id,name asc
) a
left outer join
-- max rank by id
(
select t.id,max(t.rank) as maxRank
from (
select mt.*,
case mt.id
when #curId
then #curRow := #curRow + 1
else #curRow := 1 and #curId := mt.id END
as rank
from myTable mt
join (select #curRow := 0, #curId := -1) r
order by id,name asc
) t
group by t.id
) b on a.id = b.id and b.maxRank = a.rank;