Thankyou for that explanation Michael.
I shall look into using that construct in my own code now!
Apologies to fbsd_user for my previous comments on his
coding style.
Regards
Keith Roberts
In theory, theory and practice are the same;
In practice they are not.
On Mon, 13 Mar 2006, Michael Stassen wrote:
> To: [EMAIL PROTECTED]
> From: Michael Stassen <[EMAIL PROTECTED]>
> Subject: Re: Checking for good update
>
> [EMAIL PROTECTED] wrote:
> > On Sun, 12 Mar 2006, Michael Stassen wrote:
> > >
> > > [EMAIL PROTECTED] wrote:
> > >
> > > > looks a bit strange to me.
> > > >
> > > > > $result = mysql_query($query) or die('Query couldn\'t
> > > > > executed:'.mysql_error());
> > > >
> > > > please try something like this:
> > >
> > > Why? There's nothing wrong with the above statement.
> >
> > I've never seen logic like that before. It looks to me like fbsd_user
> > is trying to use the OR operator outside an if statement.
> >
> > Is the mentioned in the php manual somewhere Michael?
> >
> > > > I've not tested this - but it looks like you are mixing
> > > > sending the
> > > > mysql query and testing for the result of the query at the
> > > > same time,
> > > > which AFAIK is not possible.
> > >
> > > You should try it. It works just fine, and isn't the problem.
> > > The
> > > problem is that you cannot treat the result of an UPDATE as if it
> > > were a
> > > SELECT.
> >
> > Regards
> > Keith Roberts
>
> Yes, this is documented. It's also standard practice (in perl and C as
> well).
>
> OR is not part of an if statement, it is a logical operator.
> <http://www.php.net/manual/en/language.operators.logical.php> "A or B"
> has a value, true or false, depending on the values of A and of B. In
> fact, if A is true, then "A or B" is certainly true, so there's no need to
> look at B at all. This short-circuit evaluation, combined with the fact
> that every assignment returns the assigned value
> <http://www.php.net/manual/en/language.expressions.php>, makes a statement
> like this possible.
>
> $result = mysql_query($query) or die('Query error:'.mysql_error());
>
> First, the function mysql_query() is called. Its return value is assigned
> to $result, *and* returned as the return value of the assignment operator
> (=). Now we know A. If mysql_query succeeded, its return value (A)
> evaluates as true, so the or operation must be true, so no need to look at
> B. If, on the other hand, A is false (mysql_query failed), we must
> evaluate B to determine the value of the "or" expression. Of course, to
> determine the value of B, we have to call the referenced function, die().
>
> Michael
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