Re: How to write such a query

Hi, Ken,

On Fri, Sep 18, 2020 at 2:46 PM Ken Tanzer <ken(dot)tanzer(at)gmail(dot)com> wrote:

> > How to find what the primary key (or UNIQUE identifier) value is
>> > for row 5 in the recordset?
>>
>> You're missing the point: as mentioned before, there is no "row 5". To
>> update the 5th record that you've fetched, you increment a counter each
>> time
>> you fetch a row, and when you read #5, do an UPDATE X SET field1 =
>> 'blarg'
>> WHERE id = <thekeyvalue>;
>>
>>
> It seems worth mentioning for benefit of the OPs question that there _is_
> a way to get a row number within a result set. Understanding and making
> good use of that is an additional matter.
>
> SELECT X.field1, Y.field2*,row_number() OVER ()* from X, Y WHERE X.id =
> Y.id -- ORDER BY ____?
>
> That row number is going to depend on the order of the query, so it might
> or might not have any meaning. But if you queried with a primary key and a
> row number, you could then tie the two together and make an update based on
> that.
>

Thank you for the info.
My problem is that I want to emulate Access behavior.

As I said - Access does it without changing the query internally (I
presume).

I want to do the same with PostgreSQL.

I'm just trying to understand how to make it work for any query

I can have 3,4,5 tables, query them and then update the Nth record in the
resulting recordset.

Access does it, PowerBuilder does it.

I just want to understand how.

Thank you.

> Cheers,
> Ken
> --
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