Posted by Dan McCullough on 10/11/05 20:29

got some code so we can see?

On 10/11/05, aaronjw@martekbiz.com <aaronjw@martekbiz.com> wrote:
> Thanks everyone. Makes sense. Now I got another issue.
>
> When I try to see if an error exists I get this:
>
> Warning: mysql_error(): supplied argument is not a valid MySQL-Link
> resource in /home/********/public_html/Store/test.php on line 14
>
> Is there a setting somewhere that I need to set to make sure this is
> available?
>
> Thanks and sorry is these are dumb-ass questions :)
>
> Aaron
>
>
> > Yes I believe that is what Richard was saying about "Trap the INSERT
> > error", you should get an error back from the database about having a
> > problem with the insert instead of showing that error you will want to
> > add some logic that when that error occurs you simply generate another
> > number.
> >
> > On 10/11/05, aaronjw@martekbiz.com <aaronjw@martekbiz.com> wrote:
> >> Hi Richard,
> >>
> >> Ok... I do already have a Unique index on the column but this process is
> >> something that I cannot echo out the error code to the user. The code is
> >> generated on the fly when an order an is placed so you can see... I
> >> can't
> >> echo out the error to the customer.
> >>
> >> Can I do an if statement IF an error is returned to try generatre
> >> another
> >> randon code and keep going until one is available? I can do this all
> >> intenrally without the customer knowing/seeing anything?
> >>
> >> Hope I am making some sense. Not trying to confuse the issue.
> >>
> >> Thanks. Appreciate your thoughts.
> >>
> >> Aaron
> >>
> >> > On Mon, October 10, 2005 3:24 pm, Dan McCullough wrote:
> >> >> create a function to check if the rndnumber=couponcode row count = 0
> >> >> if not then redo rndnumber if it does = 0 then insert rndnumber
> >> >
> >> > Noooooooooooooooooooooooooooo!
> >> >
> >> > You are creating a RACE CONDITION in which ONE user might generate a
> >> > 'valid' code, and ANOTHER user might generate a 'valid' code AT THE
> >> > SAME TIME, and then they BOTH get the same coupon code.
> >> >
> >> > The probability of this is very very very low, but still NOT zero.
> >> >
> >> > And it's the kind of thing that won't show up in testing, but sure as
> >> > God made little green apples, it WILL happen at the worst possible
> >> > time after you "go live"
> >> >
> >> > The database engine has a *TON* of code in it to avoid this kind of
> >> > Bad Thing happening.
> >> >
> >> > Use it.
> >> >
> >> > create a UNIQUE INDEX on the column that needs to be unique.
> >> >
> >> > Trap the INSERT error.
> >> >
> >> > --
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> >> >
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> >> >
> >>
> >>
> >
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