Pulling data while pivoting at the same time - sql

Question

ID | Type | Code
1 Purchase A1
1 Return B1
1 Exchange C1
2 Purchase D1
2 Return NULL
2 Exchange F1
3 Purchase G1
3 Return H1
3 Exchange I1
4 Purchase J1
4 Exchange K1
Above is sample data. What I want to return is:
ID | Type | Code
1 Purchase A1
1 Return B1
1 Exchange C1
3 Purchase G1
3 Return H1
3 Exchange I1
So if a field is null in code or the values of Purchase, Return and Exchange are not all present for that ID, ignore that ID completely. However there is one last step. I want this data to then be pivoted this way:
ID | Purchase | Return | Exchange
1 A1 B1 C1
3 G1 H1 I1
I asked this yesterday without the pivot portion which you can see here:
SQL query to return data only if ALL necessary columns are present and not NULL
However I forgot to note the last part. I tried to play around with excel but had no luck. I tried to make a temp table but the data is too large to do that so I was wondering if this could all be done in 1 sql statement?
I personally used this query with success:
select t.*
from t
where 3 = (select count(distinct t2.type)
from t t2
where t2.id = t.id and
t2.type in ('Purchase', 'Exchange', 'Return') and
t2.Code is not null
);
So how can we adjust that to include the pivot part. Is that possible?

Answer 1

Quite easily. Just use conditional aggregation:
select t.id,
max(case when type = 'Purchase' then code end) as Purchase,
max(case when type = 'Exchange' then code end) as Exchange,
max(case when type = 'Return' then code end) as Return
from t
where 3 = (select count(distinct t2.type)
from t t2
where t2.id = t.id and
t2.type in ('Purchase', 'Exchange', 'Return') and
t2.Code is not null
)
group by t.id;
This is actually simpler to express (in my opinion) using having without the subquery:
select t.id,
max(case when type = 'Purchase' then code end) as Purchase,
max(case when type = 'Exchange' then code end) as Exchange,
max(case when type = 'Return' then code end) as Return
from t
group by t.id
having max(case when type = 'Purchase' then code end) is not null and
max(case when type = 'Exchange' then code end) is not null and
max(case when type = 'Return' then code end) is not null;
Many databases would allow:
having Purchase is not null and Exchange is not null and Return is not null
But Oracle doesn't allow the use of table aliases in the having clause.

Answer 2

UPDATE - Based on discussion in the question comments, my previous query had a faulty assumption (which I carried over from what I thought I saw in the original query in the question); I've eliminated the bad assumption.
select id
, max(case when type='Purchase' then Code end) Purchase
, max(case when type='Return' then Code end) Return
, max(case when type='Exchange' then Code end) Exchange
from t
where code is not null
and type in ('Purchase', 'Return', 'Exchange')
group by id
having count(distinct type) = 3

Answer 3

I will point out again (as I did in your other thread) that analytic functions will do the job much faster - they need the base table to be read just once, and there are no explicit or implicit joins.
with
test_data ( id, type, code ) as (
select 1, 'Purchase', 'A1' from dual union all
select 1, 'Return' , 'B1' from dual union all
select 1, 'Exchange', 'C1' from dual union all
select 2, 'Purchase', 'D1' from dual union all
select 2, 'Return' , null from dual union all
select 2, 'Exchange', 'F1' from dual union all
select 3, 'Purchase', 'G1' from dual union all
select 3, 'Return' , 'H1' from dual union all
select 3, 'Exchange', 'I1' from dual union all
select 4, 'Purchase', 'J1' from dual union all
select 4, 'Exchange', 'K1' from dual
)
-- end of test data; actual solution (SQL query) begins below this line
select id, purchase, return, exchange
from ( select id, type, code
from ( select id, type, code,
count( distinct case when type in ('Purchase', 'Return', 'Exchange')
then type end
) over (partition by id) as ct_type,
count( case when code is null then 1 end
) over (partition by id) as ct_code
from test_data
)
where ct_type = 3 and ct_code = 0
)
pivot ( min(code) for type in ('Purchase' as purchase, 'Return' as return,
'Exchange' as exchange)
)
;
Output:
ID PURCHASE RETURN EXCHANGE
--- -------- -------- --------
1 A1 B1 C1
3 G1 H1 I1
2 rows selected.