は、クエリのpostgresql

Question

に参加し、「完了」を改善するクエリで私を助けてください： は、私は、テーブルの販売を次ています

customer material week value 
customer1 material1 w1  100 
customer1 material1 w2  200 
customer1 material1 w4  300 
customer1 material2 w4  200 

とテーブル週間

week 
w1 
w2 
w3 
w4 

を私はテーブルを返すクエリを記述する必要があります」完成したデータ "である。 結果テーブルでなければなりません：

customer material week value 
customer1 material1 w1  100 
customer1 material1 w2  200 
customer1 material1 w3  0 
customer1 material1 w4  300 
customer1 material2 w1  0 
customer1 material2 w2  0 
customer1 material2 w3  0 
customer1 material2 w4  200 

私はこのクエリを書くが、私は、これは最適ではないと思います。テーブルの初期化のための

select 
    dict.customer, 
    dict.material, 
    weeks.week, 
    coalesce(sales.value, 0) 
from 
    (select distinct 
     customer, 
     material 
    from 
     sales) dict 
cross join 
     weeks 
left join 
    sales on dict.customer = sales.customer and 
      dict.material = sales.material and 
      weeks.week = sales.week 

スクリプト：

CREATE TABLE public.sales 
(
    customer character varying(10), 
    material character varying(18), 
    week character varying(3), 
    value numeric 
); 

CREATE TABLE public.weeks 
(
    week character varying(3) 
); 


insert into public.sales (customer, material, week, value) 
values ('customer1', 'material1', 'w1', 100), 
    ('customer1', 'material1', 'w2', 200), 
    ('customer1', 'material1', 'w4', 300), 
    ('customer1', 'material2', 'w4', 200); 

insert into public.weeks (week) 
values ('w1'), ('w2'), ('w3'), ('w4'); 

ありがとうございました。

Answer 1

select 
    customer, 
    material, 
    week, 
    coalesce(sum(value), 0) as value 
from 
    sales 
    right join (
     (
      select distinct customer, material 
      from sales 
     ) s 
     cross join 
     weeks 
    ) s using (customer, material, week) 
group by 1,2,3 
; 
customer | material | week | value 
-----------+-----------+------+------- 
customer1 | material1 | w1 | 100 
customer1 | material1 | w2 | 200 
customer1 | material1 | w3 |  0 
customer1 | material1 | w4 | 300 
customer1 | material2 | w1 |  0 
customer1 | material2 | w2 |  0 
customer1 | material2 | w3 |  0 
customer1 | material2 | w4 | 200