From: | Ron <ronljohnsonjr(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: How to write such a query |
Date: | 2020-09-18 19:25:37 |
Message-ID: | f3ac3c95-4935-6662-27ad-a025093b5af3@gmail.com |
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Thread: | |
Lists: | pgsql-general |
On 9/18/20 1:49 PM, Igor Korot wrote:
> Hi, Adrian,
>
> On Fri, Sep 18, 2020 at 12:58 PM Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>> On 9/18/20 10:46 AM, Igor Korot wrote:
>>> Hi, Johnathan,
>>>
>>> On Fri, Sep 18, 2020 at 12:34 PM Jonathan Strong
>>> <jonathanrstrong(at)gmail(dot)com <mailto:jonathanrstrong(at)gmail(dot)com>> wrote:
>>>
>>> Are you looking to arbitrarily update the field in the fifth row, or
>>> can the row that needs to be updated be isolated by some add'l
>>> attribute? What's the use case?
>>>
>>>
>>> What do you mean?
>>> I don't have any other attributes.
>>>
>>> I want to understand how to emulate MS Access behavior, where you have a
>>> form
>>> with the arbitrary query, then you can go to any record in that form and
>>> update any field.
>>>
>>> Is it even possible from the "pure SQL" POV? Or Access is doing some
>>> VBA/DB/4GL magic?
>>>
>> When you are updating a record in a form the framework(Access in your
>> case) is using some identifier from that record to UPDATE that
>> particular record in the database. From when I used Access, I seem to
>> remember it would not give you INSERT/UPDATE capability on a form unless
>> you had specified some unique key for the records. So you need to find
>> what the key(generally a PRIMARY KEY) is and use that to do the UPDATE.
> But now the question becomes
>
> 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>;
--
Angular momentum makes the world go 'round.
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