How to escape several with in the query? - sql

Question

I need to refactor my query, but I have no idea, how to do this.
I can see several duplicates of using the same logic, but I continue to repeat this manner of querying from query to query, and I feel, that this kind of querying becomes my main frame of thinking of SQL and I don't want this.
Could you show me more acceptable variant of this query, so I won't repeat my way of thinking again?
Here it is
WITH fourth_table AS
(
WITH third_table AS
(
WITH second_table AS
(
WITH initial_table AS
(
SELECT
DISTINCT ctr.country_region, EXTRACT (YEAR FROM s.time_id)::int AS calendar_year, chn.channel_desc,
SUM(s.amount_sold) OVER (PARTITION BY ctr.country_region||chn.channel_desc||EXTRACT (YEAR FROM s.time_id)) AS amount_sold
FROM sales s
JOIN channels chn ON s.channel_id = chn.channel_id
JOIN customers c ON s.cust_id = c.cust_id
JOIN countries ctr ON c.country_id = ctr.country_id
WHERE ctr.country_region IN ('Americas','Asia', 'Europe')
AND
EXTRACT (YEAR FROM s.time_id)::int IN (1998, 1999, 2000, 2001)
ORDER BY ctr.country_region, calendar_year, chn.channel_desc
)
SELECT country_region, calendar_year, channel_desc, amount_sold,
(amount_sold/SUM(amount_sold) OVER (PARTITION BY country_region||calendar_year)*100)::decimal(10,2) AS bychannels
FROM initial_table
)
SELECT *,
LAG (bychannels, 4) OVER (ORDER BY 6) AS lower_salary
FROM second_table--correct here smth wrong
)
SELECT *, bychannels - lower_salary AS diff FROM third_table
)
SELECT country_region, calendar_year, channel_desc,
--'FM 999,999,999,990D'
LPAD(to_char(amount_sold, 'FM999,999,999,990 $'),20, ' ') AS amount_sold,
LPAD(bychannels || ' %' ,20, ' ') AS "% BY CHANNELS",
LPAD(lower_salary || ' % ' ,20, ' ') AS "% PREVIOUS PERIOD",
diff AS "% DIFF"
FROM fourth_table WHERE calendar_year NOT IN (1998);

Answer 1

You are mixing CTE (Common Table Queries) with Subqueries, the beauty of the with clause is normally the readability:
with initial_table as
(
SELECT
DISTINCT ctr.country_region, EXTRACT (YEAR FROM s.time_id)::int AS calendar_year, chn.channel_desc,
SUM(s.amount_sold) OVER (PARTITION BY ctr.country_region||chn.channel_desc||EXTRACT (YEAR FROM s.time_id)) AS amount_sold
FROM sales s
JOIN channels chn ON s.channel_id = chn.channel_id
JOIN customers c ON s.cust_id = c.cust_id
JOIN countries ctr ON c.country_id = ctr.country_id
WHERE ctr.country_region IN ('Americas','Asia', 'Europe')
AND
EXTRACT (YEAR FROM s.time_id)::int IN (1998, 1999, 2000, 2001)
ORDER BY ctr.country_region, calendar_year, chn.channel_desc
)
,second_table as
(
SELECT country_region, calendar_year, channel_desc, amount_sold,
(amount_sold/SUM(amount_sold) OVER (PARTITION BY country_region||calendar_year)*100)::decimal(10,2) AS bychannels
FROM initial_table
)
,third_table as
(
SELECT *,
LAG (bychannels, 4) OVER (ORDER BY 6) AS lower_salary
FROM second_table--correct here smth wrong
)
,fourth_table as
(
SELECT *, bychannels - lower_salary AS diff FROM third_table
)
SELECT country_region, calendar_year, channel_desc,
--'FM 999,999,999,990D'
LPAD(to_char(amount_sold, 'FM999,999,999,990 $'),20, ' ') AS amount_sold,
LPAD(bychannels || ' %' ,20, ' ') AS "% BY CHANNELS",
LPAD(lower_salary || ' % ' ,20, ' ') AS "% PREVIOUS PERIOD",
diff AS "% DIFF"
FROM fourth_table WHERE calendar_year NOT IN (1998);