Loops and Case Statements Involving Dates

On Mon, Aug 21, 2023 at 3:07 PM Anthony Apollis
<anthony.apollis@gmail.com> wrote:

Please review my code and make recommendations where needed. I have this code:
```
NUMBER OF LOOPS FOR POSTGRESQL ETL:
SELECT
CASE
WHEN (((EXTRACT(DAY FROM
((CASE
WHEN
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER)) IS NULL THEN '2020-07-01'
ELSE
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER)) + interval '1 day'
END))::timestamp - --start date
(CAST(NOW() - INTERVAL '1 day' AS DATE))::timestamp)-1) --end date
* -1)) <= 30 THEN 1
ELSE
CEIL(((EXTRACT(DAY FROM
((CASE
WHEN
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER)) IS NULL THEN '2020-07-01'
ELSE
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM system."IMETA_ZINV_AP1_Invoice_data_TA_BW"" AS WEEK_NUMBER)) + interval '1 day'
END))::timestamp - --start date
(CAST(NOW() - INTERVAL '1 day' AS DATE))::timestamp)-1) --end date
* -1)/30) --30 DAY INTERVALS UNLESS LESS
END
AS "Number of days"

“system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW”
seems like some of the characters look like double quotes, but it's
maybe not a double quote.
wiki: https://en.wikipedia.org/wiki/Quotation_mark.

On 2023-08-21 09:07:00 +0200, Anthony Apollis wrote:

Please review my code and make recommendations where needed. I have this code:
```

[complicated code snipped]

I have re-written this code to make it less complex, still doing what
it is supposed to do. I want you to review my re-written code(code
must give me report up until yesterday):
```
WITH MaxDateCTE AS (
SELECT
COALESCE(MAX(DISTINCT "CALDAY"), '2021-07-01') AS MaxDate
FROM
"system"."IMETA_ZTRNSPCST$F_Shipment_Cost_TA_BW"
)

SELECT
CASE
WHEN EXTRACT(DAY FROM (MaxDate + INTERVAL '1 day')::timestamp - (NOW() - INTERVAL '1 day')::timestamp) <= 30 THEN 1
ELSE CEIL(EXTRACT(DAY FROM (MaxDate + INTERVAL '1 day')::timestamp - (NOW() - INTERVAL '1 day')::timestamp) / 30)
END AS "Number of days"
FROM
MaxDateCTE;

So the intent is to compute how many "months" the maximum CALDAY is in
the future, with some minor twists:
* A "month" is always 30 days, not a calendar month.
* The difference is between the day after the given date and yesterday -
so it's shifted by one day (today + 30 days already counts as 2
months)
* the minimum is 1.
?

Then this can be simplified further:

* MAX(DISTINCT "CALDAY") can be simplified to just MAX("CALDAY").

* The CASE can be eliminated and replaced by
GREATEST(CEIL(EXTRACT(DAY FROM (MaxDate + INTERVAL '1 day')::timestamp - (NOW() - INTERVAL '1 day')::timestamp) / 30), 1)

hp

--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp@hjp.at | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"

Since this code is in a loop, consider using clock_timestamp() instead of
now(). It might not matter in this situation, though.

On 8/21/23 02:07, Anthony Apollis wrote:

*Please review my code and make recommendations where needed. I have this
code: *```
NUMBER OF LOOPS FOR POSTGRESQL ETL:
SELECT
CASE
WHEN (((EXTRACT(DAY FROM
((CASE
WHEN
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER)) IS NULL THEN '2020-07-01'
ELSE
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER)) + interval '1 day'
END))::timestamp - --start date
(CAST(NOW() - INTERVAL '1 day' AS DATE))::timestamp)-1) --end date
* -1)) <= 30 THEN 1
ELSE
CEIL(((EXTRACT(DAY FROM
((CASE
WHEN
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER)) IS NULL THEN '2020-07-01'
ELSE
(SELECT DISTINCT "CALDAY" FROM “system”.”IMETA_ZACTPRIC1_Cust_Pricing_TA_BW” AS WEEK_NUMBER
WHERE
WEEK_NUMBER."CALDAY" = (SELECT MAX(DISTINCT "CALDAY") AS "Calendar day" FROM system."IMETA_ZINV_AP1_Invoice_data_TA_BW"" AS WEEK_NUMBER)) + interval '1 day'
END))::timestamp - --start date
(CAST(NOW() - INTERVAL '1 day' AS DATE))::timestamp)-1) --end date
* -1)/30) --30 DAY INTERVALS UNLESS LESS
END
AS "Number of days"
I have re-written this code to make it less complex, still doing what it is supposed to do. I want you to review my re-written code(code must give me report up until yesterday):
```
WITH MaxDateCTE AS (
SELECT
COALESCE(MAX(DISTINCT "CALDAY"), '2021-07-01') AS MaxDate
FROM
"system"."IMETA_ZTRNSPCST$F_Shipment_Cost_TA_BW"
)

SELECT
CASE
WHEN EXTRACT(DAY FROM (MaxDate + INTERVAL '1 day')::timestamp - (NOW() - INTERVAL '1 day')::timestamp) <= 30 THEN 1
ELSE CEIL(EXTRACT(DAY FROM (MaxDate + INTERVAL '1 day')::timestamp - (NOW() - INTERVAL '1 day')::timestamp) / 30)
END AS "Number of days"
FROM
MaxDateCTE;

**
*Full Code can be found here:
https://drive.google.com/file/d/1NaoaK0z3s3cfYilAdH4stJ1F6mq6Sc4n/view?usp=sharing*

--
Born in Arizona, moved to Babylonia.