RE: INSERT Trigger to check for existing records : Does this do what I hope it is doing? - Mailing list pgsql-general

Adrian,

Thanks for your detailed response. That's very kind and much appreciated.

1. OK that's just me groping for a RETURN statement that doesn't throw a rod. I don't actually need to return anything
asthe goal of the FUNCTION (for the moment)  is to perform updates to a table. It might be nice to return some sort of
confirmationbut it's not necessary. Apparently I don't fully understand the RETURN concept (oh really? 😉. Any
suggestionswhere to research or read? 

2. I have two tables:
    a) sfdc which is the baseline - doesn't change -  isn't updated by this FUNTION
    b) hygiene_119 a new table which has some records (~80%) which are identical to those already in sfdc.

The logic flow is:
        i) SELECT the dealids from hygiene_119 (latest or new  report dated 11/9)
        ii) compare those hygiene_119.dealids with the existing sfdc.dealids  -  hence the IF $1 (one result from the
hygiene_119.dealdidSELECT) is IN (matches) any of the sfdc.dealids THEN 
        iii) UPDATE hygiene_119 SET status = 'SAME' WHERE dealid = $1; --flag that hygiene_119 record as the SAME or a
duplicaterecord 
        iv) ELSE UPDATE hygiene_119 SET status = 'NEW' WHERE dealid = $1; --flag that hygiene_119 record as NEW  or a
newrecord 
    Once I have inspected the "NEW" records in hygiene_119 I will INSERT then into sfdc. Then rinse and repeat each
weekwith a new report. 

3. Not positive the IF is doing what I want,  but if I copy a sfdc.dealid into the same_test() parameter field the
FUNTIONdoes update the hygiene_119.status field properly. To me, it appears I just need a way to iterate through and
insertone hygiene_119.dealid in the same_test parameter field. Then the UPDATE should flag all the hygiene_119 records
asSAME or NEW. Obviously I don't REALLY need both flags as the absence of a flag would indicate status too. 

Does that articulate the thought process adequately?

Best,

Hagen


-----Original Message-----
From: Adrian Klaver <adrian.klaver@aklaver.com>
Sent: Wednesday, November 25, 2020 9:07 AM
To: Hagen Finley <hagen@datasundae.com>; pgsql-general@lists.postgresql.org
Subject: Re: INSERT Trigger to check for existing records : Does this do what I hope it is doing?

On 11/25/20 7:41 AM, Hagen Finley wrote:
> Folks,
>
> Just a quick question. *Using this FUNCTION:*
>
>     CREATE OR REPLACE FUNCTION same_test(did numeric)
>     RETURNS numeric AS $$
>     BEGIN
>        IF $1 IN
>            (SELECT dealid from sfdc)
>        THEN
>          UPDATE hygiene_119 SET status = 'SAME';
>        ELSE
>            UPDATE hygiene_119 SET status = 'NEW';
>        END IF;
>     RETURN NULL;
>     END;
>     $$ LANGUAGE plpgsql;

The above is broken in multiple ways:

1) You have RETURNS numeric and then RETURN NULL; This means you will not actually return anything

2) You have the input argument did but you never use it to restrict your UPDATEs.

3) Not sure the logic in the IF actually works even if you filtered by did. This assumes that there will always be a
rowin hygiene_119 that matches one in hygiene_112. Given that you setting a 'NEW' flag I'm guessing that is not the
case.

You will need to sketch out the thought process at work here before we can go any further with this.



>
> *Does the following query input the the dealids that result from the
> SELECT statement into the parameter of the sames_test() FUNCTION?*

>
> Select dealid sametest(dealid) FROM hygiene_123;

Have no idea what that is supposed to do?

If you want to use the function(after fixing it) you would have to do:

select * from some_test(some_number);

>
> I doubt it does (my query runs a /long time)/ :-). I know I can utilize
> python to push SELECT results into a array and then run a 'FOR d in
> dealids' LOOP to feed the FUNCTION parameter but I'd like to learn how
> to do that with nested SQL statements or FUNCTIONS.
>
> Thanks!
>
>
> Hagen
>

--
Adrian Klaver
adrian.klaver@aklaver.com