Thank you Michael. I learned a lot from your detailed explanation
of how the update and select functions work in relation to
checking for good execution.
I used
if (mysql_affected_rows() == 1)
and got the results I was after.
I am stilling having problem with users browser
caching the screen, but will post that as separate question.
Again thanks for your expert help.
-----Original Message-----
From: Michael Stassen [mailto:Michael.Stassen@stripped]
Sent: Monday, March 13, 2006 4:18 AM
To: mysql@stripped
Cc: mysql@stripped
Subject: Re: Checking for good update
mysql@stripped wrote:
> On Sun, 12 Mar 2006, Michael Stassen wrote:
>>
>>mysql@stripped 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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