Getting unique Ids but not loose any data using SQL - sql

Question

Given a table sale where id is not unique:
id name item quantity
1 Darsh shoes 5
2 Liyah oil 1
2 Eiliyah watch 1
3 Zakaria notebook 2
3 Elliot shirt 3
4 Reese bag 1
I need to select all unique ids for a row and not loose any data(like for id in (2,3) where both name,item and quantity should be displayed in same row).Also there are maximum of 2 same id in sale table.
I tried using row_number() to get some unique pattern(s).
From this query :
Select a.id,a.name,a.item,a.quantity,b.name as name2,b.item as item2,b.quantity as quantity2
,row_number() over(partition by a.id order by a.id) as f1
,row_number() over(partition by a.name order by a.id) as f2
from sale a inner join sale b on a.id = b.id
I got this
id name item quantity name2 item2 quantity2 f1 f2
1 Darsh shoes 5 Darsh shoes 5 1 1
2 Eiliyah watch 1 Liyah oil 1 2 1
2 Eiliyah watch 1 Eiliyah watch 1 4 2
3 Elliot shirt 3 Zakaria notebook 2 2 1
3 Elliot shirt 3 Elliot shirt 3 4 2
2 Liyah oil 1 Eiliyah watch 1 3 1
2 Liyah oil 1 Liyah oil 1 1 2
4 Reese bag 1 Reese bag 1 1 1
3 Zakaria notebook 2 Elliot shirt 3 3 1
3 Zakaria notebook 2 Zakaria notebook 2 1 2
Now here the problem,If I filter f1,f2 and use IIF for remove repetitive data using this query :
Select id,name,item,quantity
,iif(name = name2,NULL,name2) as name2
,iif(item = item2,NULL,item2) as item2
,iif(quantity = quantity2,NULL,quantity2) as quantity2
from (
Select a.id,a.name,a.item,a.quantity,b.name as name2,b.item as item2,b.quantity as quantity2
,row_number() over(partition by a.id order by a.id) as f1
,row_number() over(partition by a.name order by a.id) as f2
from sale a inner join sale b on a.id = b.id
)t
where (f1=1 and f2=1) or(f1=3 and f2=1)
order by id
then quantity2 is (null) in 2nd row as shown below.
id name item quantity name2 item2 quantity2
1 Darsh shoes 5 NULL NULL NULL
2 Liyah oil 1 Eiliyah watch NULL
3 Zakaria notebook 2 Elliot shirt 3
4 Reese bag 1 NULL NULL NULL
So, there can be same quantity for different item and name.
Expected result:
id name item quantity name2 item2 quantity2
1 Darsh shoes 5 NULL NULL NULL
2 Liyah oil 1 Eiliyah watch 1
3 Zakaria notebook 2 Elliot shirt 3
4 Reese bag 1 NULL NULL NULL
Please help me.
Thanks!

Answer 1

One method is conditional aggregation . . . if you know that there are at most two duplicates per id:
select id,
max(case when seqnum = 1 then name end) as name_1,
max(case when seqnum = 1 then item end) as item_1,
max(case when seqnum = 1 then quantity end) as quantity_1,
max(case when seqnum = 2 then name end) as name_2,
max(case when seqnum = 2 then item end) as item_2,
max(case when seqnum = 2 then quantity end) as quantity_2
from (select s.*,
row_number() over (partition by id order by id) as seqnum
from sale s
) s
group by id;

Answer 2

As per your expected result .You can create temp(or Intermediate table) and as there are maximum of same two id ,then this can be your answer:
select *,row_number() over (partition by id order by id) as u_id into #test from sale
select * from (select * from #test where u_id=1) a
left join (select * from #test where u_id=2)b
on a.id = b.id