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Message-ID: <4729a93e-7d39-4837-8e9b-8ecc2e628b81@aklaver.com>
Date: Sun, 19 Oct 2025 09:59:39 -0700
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Subject: Re: Convert date and time colums to datetime
To: Rich Shepard <rshepard@appl-ecosys.com>, pgsql-general@postgresql.org
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 <b15aa3a-f878-cb2-1749-b418de4fabe@appl-ecosys.com>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
In-Reply-To: <b15aa3a-f878-cb2-1749-b418de4fabe@appl-ecosys.com>
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On 10/19/25 09:35, Rich Shepard wrote:
> On Sun, 19 Oct 2025, Adrian Klaver wrote:
> 
>> 2) If you really need a timestamp the work is already done, instead of 
>> building on the fly.
> 
> Adrian,
> 
> As each row in the table already has both a date column and a time column I
> don't know if I 'really' need a timestamp. When would a timestamp be really
> needed?

I would say the fact you are asking is an indication you might need it.

> 
>> select ('10/19/2025'::date + '07:50'::time)::timestamptz;
> 
> Yes, I saw that on the doc page. This requires manually changing each 
> row in
> the table rather than using a date/time condition/function to to create the
> single timestamp column. So, apparently there's not a way to modify the
> table other than by hand.

1) Again you seem to be establishing a need for combined value.

2) Not sure how you  do "...date/time condition/function to to create 
the single timestamp column" without creating a column?

If you meant creating a timestamp value then I point you at my original 
post and:

"2) If you really need a timestamp the work is already done, instead of 
building on the fly."

Doing the one time change to add a timestamp field to the table and then 
do the UPDATE of date + time to populate it versus calculating it every 
time you need the value. Of course moving forward you would need to 
change the code that INSERTs new values to use a timestamp instead of a 
date and a time value.

> 
> Thanks,
> 
> Rich
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com