Counting current and longest streaks of a given value - sql

Question

I have 2 tables Person (ID, NAME, CLAN_ID) and DailyScore (PERSON_ID, CLAN_ID, DAY_NUMBER, SCORE).
SCORE can take the values "A", "B", "C" or "-" ("-" means absent).
I need to make 2 separate queries to get, for a given CLAN_ID:
the current streak of a given score (let's say A, e.g.) for each Person and the name of the Person, ordered by streak length DESC
the longest ever streak of a given score (let's say A, e.g.) for each Person and the name of the Person, ordered by streak length DESC
An important constraint is that "-" SCORES are ignored, as they represent absences, not real Scores.
Example data:
Table Person:
_ID NAME CLAN_ID
1 John 11
2 Alice 11
3 Bob 12
4 Sara 12
Table DailyScore:
PERSON_ID CLAN_ID DAY_NUMBER SCORE
1 11 1 A
1 11 2 A
1 11 3 A
1 11 4 C
1 11 5 A
2 11 1 B
2 11 2 C
2 11 3 B
2 11 4 A
2 11 5 A
3 12 1 A
3 12 2 A
3 12 3 A
3 12 4 A
3 12 5 B
4 12 1 C
4 12 2 B
4 12 3 C
4 12 4 A
4 12 5 -
Desired result example 1 (CLAN_ID=11, SCORE=A):
Current streak:
Alice 2
John 1
Longest ever streak:
John 3
Alice 2
Desired result example 2 (CLAN_ID=12, SCORE=A):
Current streak:
Sara 1*
Bob 0
*since "-" are ignored, Sara has a current streak of 1 A score
Longest ever streak:
Bob 4
Sara 1
Edit:
In case it helps, here's this example in SQL Fiddle: http://sqlfiddle.com/#!7/2ed69/2

Answer 1

The first query can be:
select
id, name, max(s) as streak
from (
select
p.id,
p.name,
count(*) over(partition by p.id order by s.day_number desc) as c,
sum(case when s.score = 'A' then 1 else 0 end)
over(partition by p.id order by s.day_number desc) as s
from person p
join dailyscore s on s.person_id = p.id
) x
where c = s
group by id, name