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
THEN1 
>         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!"