Re: Loops and Case Statements Involving Dates

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(at)hjp(dot)at | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"