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* Using Transaction with if-else in prepared statement
@ 2022-05-25 11:12 Hui Jackson <[email protected]>
2022-05-25 18:03 ` Re: Using Transaction with if-else in prepared statement Steve Midgley <[email protected]>
2022-05-25 23:35 ` Re: Using Transaction with if-else in prepared statement hubert depesz lubaczewski <[email protected]>
0 siblings, 2 replies; 4+ messages in thread
From: Hui Jackson @ 2022-05-25 11:12 UTC (permalink / raw)
To: [email protected]
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.
const coin = 10
const senderId = 1
const receiverId = 2
await pgPool.query(`
DO $$
BEGIN
if (SELECT coin from app_user where id = $1) >= $3 THEN
UPDATE app_user set coin = coin - $3 where id = $1;
UPDATE app_user set coin = coin + $3 where id = $2;
INSERT INTO coin_history(sender_id, receiver_id, amount) VALUES
($1, $2, $3)
END IF;
END;
$$`,[senderId, receiverId, coin]);
Error (node:10044) UnhandledPromiseRejectionWarning: error: bind message
supplies 3 parameters, but prepared statement "" requires 0
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Using Transaction with if-else in prepared statement
2022-05-25 11:12 Using Transaction with if-else in prepared statement Hui Jackson <[email protected]>
@ 2022-05-25 18:03 ` Steve Midgley <[email protected]>
1 sibling, 0 replies; 4+ messages in thread
From: Steve Midgley @ 2022-05-25 18:03 UTC (permalink / raw)
To: Hui Jackson <[email protected]>; +Cc: pgsql-sql <[email protected]>
On Wed, May 25, 2022 at 4:13 AM Hui Jackson <[email protected]> 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.
>
> const coin = 10
> const senderId = 1
> const receiverId = 2
> await pgPool.query(`
> DO $$
> BEGIN
> if (SELECT coin from app_user where id = $1) >= $3 THEN
> UPDATE app_user set coin = coin - $3 where id = $1;
> UPDATE app_user set coin = coin + $3 where id = $2;
> INSERT INTO coin_history(sender_id, receiver_id, amount)
> VALUES ($1, $2, $3)
>
> END IF;
> END;
> $$`,[senderId, receiverId, coin]);
>
> Error (node:10044) UnhandledPromiseRejectionWarning: error: bind message
> supplies 3 parameters, but prepared statement "" requires 0
>
For debugging, you might try to sending each select, update, and insert in
separate NodeJS query statements. You can do the IF work in NodeJS via a
select for data from Pg.
But at the core of your problem I believe is that you are not configuring
the postgres statement to receive parameters, but your injecting parameters
from Node. From the Pg docs on prepared statements:
https://www.postgresql.org/docs/current/sql-prepare.html
PREPARE fooplan (int, text, bool, numeric) AS
INSERT INTO foo VALUES($1, $2, $3, $4);
EXECUTE fooplan(1, 'Hunter Valley', 't', 200.00);
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Using Transaction with if-else in prepared statement
2022-05-25 11:12 Using Transaction with if-else in prepared statement Hui Jackson <[email protected]>
@ 2022-05-25 23:35 ` hubert depesz lubaczewski <[email protected]>
2022-05-26 10:00 ` Re: Using Transaction with if-else in prepared statement Hui Jackson <[email protected]>
1 sibling, 1 reply; 4+ messages in thread
From: hubert depesz lubaczewski @ 2022-05-25 23:35 UTC (permalink / raw)
To: Hui Jackson <[email protected]>; +Cc: [email protected]
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
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: Using Transaction with if-else in prepared statement
2022-05-25 11:12 Using Transaction with if-else in prepared statement Hui Jackson <[email protected]>
2022-05-25 23:35 ` Re: Using Transaction with if-else in prepared statement hubert depesz lubaczewski <[email protected]>
@ 2022-05-26 10:00 ` Hui Jackson <[email protected]>
0 siblings, 0 replies; 4+ messages in thread
From: Hui Jackson @ 2022-05-26 10:00 UTC (permalink / raw)
To: [email protected]; [email protected]; +Cc: [email protected]
Concluded both methods shared:
1. one query per each call for using prepared statement
await pgPool.query('BEGIN;');
const sender = (await pgPool.query('SELECT coin from app_user where id =
$1;',[senderId])).rows[0];
if(sender.coin >= amount){
await pgPool.query('UPDATE app_user set coin = coin - $1 where id = $2;',[
coin, senderId]);
await pgPool.query('UPDATE app_user set coin = coin + $1 where id = $2;',[
coin, receiverId]);
await pgPool.query('INSERT INTO coin_history(sender_id, receiver_id,
amount) VALUES ($1, $2, $3)',[senderId, receiverId, coin]);
await pgPool.query('COMMIT;');
}else{
await pgPool.query('END;');
}
2. Use constraint
CREATE TABLE app_user(
id integer,
coin numeric CHECK (coin >= 0)
);
hubert depesz lubaczewski <[email protected]> 於 2022年5月26日週四 上午7:35寫道：
> 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
>
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2022-05-26 10:00 UTC | newest]
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2022-05-25 11:12 Using Transaction with if-else in prepared statement Hui Jackson <[email protected]>
2022-05-25 18:03 ` Steve Midgley <[email protected]>
2022-05-25 23:35 ` hubert depesz lubaczewski <[email protected]>
2022-05-26 10:00 ` Hui Jackson <[email protected]>
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