SQL Server: how to get this result from this table (example inside) - sql

Question

I would like to ask you guys how would you do a query to show the data of this table:
week name total
==== ====== =====
1 jon 15.2
1 jon 10
1 susan 10
1 howard 9
1 ben 10
3 ben 30
3 susan 10
3 mary 10
5 jon 10
6 howard 12
7 tony 25.1
8 tony 7
8 howard 10
9 susan 6.2
9 howard 9
9 ben 10
11 howard 10
11 howard 10
like this:
week name total
==== ====== =====
1 ben 10
1 howard 9
1 jon 25.2
1 mary 0
1 susan 10
1 tony 0
3 ben 30
3 howard 0
3 jon 0
3 mary 10
3 susan 10
3 tony 0
5 ben 0
5 howard 0
5 jon 10
5 mary 0
5 susan 0
5 tony 0
6 ben 0
6 howard 12
6 jon 0
6 mary 0
6 susan 0
6 tony 0
7 ben 0
7 howard 0
7 jon 0
7 mary 0
7 susan 0
7 tony 25.1
8 ben 0
8 howard 10
8 jon 0
8 mary 0
8 susan 0
8 tony 7
9 ben 10
9 howard 9
9 jon 0
9 mary 0
9 susan 6.2
9 tony 0
11 ben 0
11 howard 20
11 jon 0
11 mary 0
11 susan 0
11 tony 0
I tried something like:
select t1.week_id ,
t2.name ,
sum(t1.total)
from xpto as t1 ,
xpto as t2
where t1.week_id = t2.week_id
group by t1.week_id, t2.name
order by t1.week_id, t2.name
But I'm failing to understand the "sum" part and I can't figure out why...
Any help would be very appreciated. Thanks in advance, and sorry for my english.

Answer 1

you might try something like the following:
select week = w.week ,
name = n.name ,
sum_total = coalesce( sum( d.total ) , 0 )
from ( select distinct week from my_table ) w
cross join ( select distinct name from my_table ) n
left join my_table d on d.week = w.week
and d.name = n.name
group by w.week ,
n.name
order by 1,2
The cross join of first two derived tables constructs their cartesian product: all week and all names from the table, regardless of whether or not a particular week/name combination exists.
We then take that, join it against the actual data rows and summarize it, using coalesce() to collapse any null results from the aggregate function sum() to 0.

Answer 2

As I understood you you want to show all weeks and all names across all table regardless whether they were entered for the week or not. To do so you will need to first build a list of all names and week, cross join them and then join them to the list of totals, like this:
;with names as (select distinct name from xpto),
weeks as (select distinct week from xpto),
totals as (select week, name, sum(total) as total
from xpto group by week, name)
select w.week, n.name, coalesce(total, 0) as total
from names n cross join weeks w
left join totals t on t.name=n.name and w.week = t.week
order by 1,2
SQL Fiddle

Answer 3

I've edited my answer because I now understand what you want to do a bit better.
I prefer doing things in several steps rather than trying to do several transformations of data with a single join or subquery. So I would approach this like this:
;
with Weeks as (
select distinct Week_id
from xpto
)
, Names as (
select distinct Name
from xpto
)
, Scores as (
select week_id
, name
, score = sum(t1.score)
from xpto t1
group by
t1.week_id
, t1.name
)
, WeeksAndNames as (
select week_id
, name
from Weeks
cross join Names
)
-- The final query!
select wan.week_id
, wan.name
, total = COALESCE(s.total,0)
from WeeksAndNames wan
left join Scores s
on wan.week_id = s.week_id
and wan.name = s.name
order by
wan.week_id
, wan.name
Lengthy, I'll grant you, and you can probably condense it. But this shows each step you need to go through to transform your data into the list you want.