Lester Caine wrote:

> I'm having a number of giggley little problems which are causing agro a
> few times a week across some sites while some never have the problem at all.
>
> The one that was spotted today is quite simple. Get ID from generator,
> Add ticket with that ID, then process ticket.
>
> "INSERT INTO TICKET ( TICKET_ID, TICKET_REF, TICKET_NO, OFFICE, ROOM,
> STAFF_ID, INIT_ID, CALLER_ID, APPLET )
> VALUES ( $ticid, 'NOW', (SELECT COALESCE(MAX(TICKET_NO)+1, 1) FROM
> CURRENT_DAY
> WHERE OFFICE = $office AND TICKET_NO BETWEEN 0 AND 9999),
> $office, 0, 0, 0, 0, ' ' )";
>
> I know that the MAX(TICKET_NO)+1 is not very safe, but the script seems
> to be getting run TWICE as I get TWO ID's, but the same TICKET_NO with
> an almost identical 'NOW'.
>
> Anybody any ideas what can be happening. Is it possible that PHP is
> running a script twice with two different transactions, from the same
> browser (IE of cause) and the second run does not see the commit of the
> first run? If that makes sens? I can't explain these occasional
> duplicates any other way, as once the ticket is added the user gets a
> 'clear ticket before adding a new one' and also the Add Ticket button is
> not present on the page that Add Ticket goes to!

it sounds like 2 different insertions (via 2 different requests) where
the transactions are overlapping and the results of the one that started first
is not being seen by the one start second... I really recommend a generator
for the TICKET_NO.

>
> Anyone having similar strange niggles?
>