How to use transaction with PQexecPrepared libpq

Asked Nov 14 '18 at 22:05

Active Nov 14 '18 at 22:31

Viewed 1,091 times

I'm new to postgresql and would like to ask how to do a transaction using BEGIN, COMMIT and PQexecPrepared. In my program, I have to update many tables before COMMIT. I do understand that we need to use:

1. PQexec(conn,"BEGIN");
2. execute some queries
3. PQexec(conn,"COMMIT");

I had first tried by using PQexecParams, it worked:

PQexec(conn,"BEGIN");
PQexecParams(conn,  "INSERT INTO Cars (Id,Name, Price) VALUES ($1,$2,$3)", 
                     3, NULL, parValues, NULL , NULL, 0 );
PQexec(conn,"COMMIT");

However when I had tried by using PQexecPrepared, my table Cars wasn't updated after COMMIT (of course it worked in autocommit mode without BEGIN &COMMIT )

PQexec(conn,"BEGIN");
PQprepare(conn,"teststmt",  "INSERT INTO Cars (Id,Name, Price) VALUES ($1,$2,$3)", 3, NULL );
PQexecPrepared(conn, "teststmt", 3, parValues,NULL, NULL,0);   
PQexec(conn,"COMMIT");

Do you have any advice in this case?

edited Nov 14 '18 at 22:31

asked Nov 14 '18 at 22:05

muocdich

Did you check for errors? – Laurenz Albe Nov 14 '18 at 22:10
I did checked. There was no error. – muocdich Nov 14 '18 at 22:16
What you show looks correct. I think you should post your whole code (ideally a minimal version that exhibits the problem) so somebody can spot the bug. – Laurenz Albe Nov 15 '18 at 06:00
Thanks. I have updated from Postgresql 9.6 to 11.1 and my program works. – muocdich Nov 16 '18 at 10:44
Then there must have been something wrong with your installation, since this hasn't changed in ages. Anyway, glad it works for you now. – Laurenz Albe Nov 16 '18 at 11:52

How to use transaction with PQexecPrepared libpq

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