Date: Thu, 26 May 2022 01:35:56 +0200
From: hubert depesz lubaczewski <depesz@depesz.com>
Sender: depesz@depesz.com
To: Hui Jackson <jackhts4@gmail.com>
Cc: pgsql-sql@lists.postgresql.org
Subject: Re: Using Transaction with if-else in prepared statement
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On Wed, May 25, 2022 at 07:12:49PM +0800, Hui Jackson wrote:
> I am trying to make transaction in nodejs
> The logic will be check if sufficient coin in sender's amount, if
> sufficient then do transaction.
> I am new to postgres, not sure if this is a right way to do so, if you have
> a better solution, please let me know, thank you.

I would do i by issuing *only*
INSERT INTO coin_history(sender_id, receiver_id, amount) VALUES
and then changing coin data with triggers plus adding constraints that
app_user.coin can never be < 0.

depesz