Group by date quarters while getting a CSV list of ID's using xml or with cross apply, Sql Server

Language: Layout:

declare @PeriodTable table (ID int identity(10,1) primary key, StartDate date, EndDate date);

insert into @PeriodTable (StartDate, EndDate) values
('2017/1/3','2017/2/2'),('2017/2/3','2017/3/2'),('2017/3/3','2017/4/2'),
('2017/4/3','2017/5/2'),('2017/5/3','2017/6/2'),('2017/6/3','2017/7/2'),
('2017/7/3','2017/8/2'),('2017/8/3','2017/9/2'),('2017/9/3','2017/10/2'),
('2017/10/3','2017/11/2'),('2017/11/3','2017/12/2'),('2017/12/3','2018/1/2'),
('2018/1/3','2018/2/2'),('2018/2/3','2018/3/2'),('2018/3/3','2018/4/2');

-- method 1
select 
stuff(
 (select concat(',',tid.ID)
  from @PeriodTable tid
  where datepart(quarter,tid.Startdate) = datepart(quarter,t.Startdate)
    and datepart(year,tid.Startdate) = datepart(year,t.Startdate)
  for xml path(''), type).value('.', 'varchar(max)')
 ,1,1,'') IdList,
min(StartDate) as FirstStartDate, max(EndDate) as LastEndDate
from @PeriodTable t
group by datepart(year,Startdate), datepart(quarter,Startdate)
order by FirstStartDate;

-- method 2, using a cross apply
select 
stuff(max(Ids),1,1,'') as IdList, min(StartDate) as FirstStartDate, max(EndDate) as LastEndDate
from @PeriodTable t
cross apply (
   select concat(',',tid.ID)
   from @PeriodTable tid
   where datepart(quarter,tid.Startdate) = datepart(quarter,t.Startdate)
     and datepart(year,tid.Startdate) = datepart(year,t.Startdate)
   for xml path('')) List(Ids)
group by datepart(year,Startdate), datepart(quarter,Startdate)
order by FirstStartDate;

View schema
Execution time: 0,02 sec, rows selected: 10, rows affected: 15, absolute service time: 0,17 sec

Group by date quarters while getting a CSV list of ID's using xml or w...