Posted by Rasmus Lerdorf on 11/26/22 11:16

Kristen G. Thorson wrote:
> Following is a snippet of code that I am trying to debug. Most of the
> time, the variable $sn (set on the last line), correctly contains the
> variable $this_customer_num. On some occasions, however, it does not
> contain $this_customer_num. I cannot figure out what may be happening
> that this value is missing around 1-10% of the time.
>
>
> <?php
>
> $memberchecker=mysql_query("SELECT id, password, customer_num FROM
> logins WHERE email = '$email'" );
> //email is unique and not null
>
> if (!$memberchecker) {
> //handle error
>
> } else {
>
> if (mysql_num_rows($memberchecker) >= 1) {
>
> while ($row = mysql_fetch_array($memberchecker)) {
>
> $this_login_password=$row[password];
>
> if ($this_login_password==$password) {
> //$password is a form variable (yes register_globals is
> on...*sigh*)
>
> $this_customer_num=$row[customer_num];
>
> $companycheck=mysql_query("SELECT priority, cash_price
> FROM customers WHERE customer_num='$this_customer_num'"); //customer_num
> is primary key, so unique and not null
>
> if (!$companycheck) {
>
> //handle error
>
> } else {
>
> if (mysql_num_rows($companycheck) == 1) {
>
> while ($cow = mysql_fetch_array($companycheck)) {
>
> $id=$row[id];
> $priority=$cow[priority];
> $cp=$cow[cash_price];
> $sn=date(Sz).$this_customer_num.time();
> ?>
>
>
> Before anyone yells at me, no I did not write this code. I first
> thought there might be a problem with the array keys not being quoted,
> but if that were the case, and an empty string were assigned to
> $this_customer_num, then I should not be able to pass the second query,
> since there are no empty string customer_num entries (all of them are at
> least 9 characters in length).
>
> I have been unable to reproduce an instance where $sn is missing the
> $this_customer_num variable, and I'm stuck in a kind of political
> situation where I can only make recommendations, and not change the code
> myself.
>
> Suggestions on where to start looking? Thanks in advance.
>

$companycheck can easily be non-false and contain no rows. A query that
doesn't match any rows is not a failure, it is simply an empty result
set. So you wouldn't get into the //handle error code there and your
mysql_num_rows() wouldn't be 1. This would appear to be possible if
there was some sort of mismatch between the customer ids in the login
table and the customers table. A bit more error checking should make it
obvious.

-Rasmus

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