[FIXED] How can I get weekly sales for every salesman

Issue

I have a table like below (tablename: sales)

sales_datetime	sales	salesman
2022-08-01 09:00:00	100	John
2022-08-01 11:00:00	200	John
2022-08-02 10:00:00	100	Peter
2022-08-02 13:00:00	300	John
2022-08-04 14:00:00	300	Peter
2022-08-05 12:00:00	100	John
2022-08-05 16:00:00	200	John

From that table I want to make a summary sales for 5 days period for each salesman. So the summary table that I want is look like this

periode	total_sales	salesman
2022-08-01	300	John
2022-08-01	0	Peter
2022-08-02	300	John
2022-08-02	100	Peter
2022-08-03	0	John
2022-08-03	0	Peter
2022-08-04	0	John
2022-08-04	300	Peter
2022-08-05	300	John
2022-08-05	0	Peter

I have created following query (PSQL) but the results were not same as I want. Assume today is 2022-08-05

with dateseries as 
(select generate_series(current_date-'4 days'::interval,
   current_date::date,
   '1 day'::interval)::date as periode)
select d.periode,coalesce(sum(s.sales),0) as total_sales,s.salesman from dateseries d
left outer join sales s
on d.periode=s.sales_datetime::date
group by d.periode, s.salesman order by d.periode

results:

periode	total_sales	salesman
2022-08-01	300	John
2022-08-02	300	John
2022-08-02	100	Peter
2022-08-03	0	(NULL)
2022-08-04	300	Peter
2022-08-05	300	John

Any advices would be so great. Thank you

Solution

Step by step first aggregate the daily sales per salesperson (aggregated_sales CTE), create a list of days to report (days CTE), create a list of salesmen (salesmen CTE) and then query the sales for each day/salesman pair.

with aggregated_sales as 
(
 select sales_datetime::date sales_date, sum(sales) sales, salesman 
 from sales group by sales_datetime::date, salesman
),
days(sales_date) as 
(
 select d::date 
 from generate_series('2022-08-01', '2022-08-08', interval '1 day') d
),
salesmen (salesman) as 
(
 select distinct salesman from sales
)
select sales_date, coalesce(sales, 0) sales, salesman 
from (select * from days cross join salesmen) fl 
left outer join aggregated_sales ags using (sales_date, salesman);

The query may be shorter if CTEs are inlined yet I think that clarity and readability are more important than mere size.

In order to "make a summary sales for 5 days period for each salesman" replace generate_series('2022-08-01', '2022-08-08', interval '1 day') with generate_series(current_date - 4, current_date, interval '1 day').

Answered By - Stefanov.sm

Answer Checked By - Marie Seifert (PHPFixing Admin)