Error Log states that I have MySQL connect error, yet script runs fine

Question

Hello All,

First, thanks for all the help I've received so far from StackOverflow. I've learned much.

Once again, I'm posing a rudimentary question that I've searched on, but cannot find the exact answer to. Here or on PHP.net.

It's sort of like what this guy asked, but not exactly: http://stackoverflow.com/questions/288603/mysql-throwing-query-error-yet-finishing-query-just-fine-why

So, I saw my errorlog ballooning up when I checked my site directory and opened to notice that a bunch of errors have been recorded since I wrote this new Admin area. I know something is obviously awry with my scripting for the error to be thrown, but the weird thing is, the script actually runs through and pulls all the data I need without breaking.

The log contains:

PHP Warning: mysql_query() [function.mysql-query]: Access denied for user 'someuser'@'localhost' (using password: NO) in /home/mysite/adminconsole.php on line 15

I don't get that because that very line is where I setup my connection... the exact same way I do it everywhere else on the site with no problem.

After that error, I have these thrown at the same time

[09-Apr-2010 08:44:18] PHP Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /home/mysite/adminconsole.php on line 15

[09-Apr-2010 08:44:18] PHP Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/mysite/adminconsole.php on line 16

From what I read in the other guys thread, the problem is the contents of the query maybe? Maybe my query is malformed?

Thanks so much for any guidance you can provide.

-Rob

ADD: To Dominic

Dominic

session_start();
if (isset($adminusr))
{
mysql_connect("localhost","user","pw") or die(mysql_error());
mysql_select_db("my_db") or die(mysql_error());
}

else    {
header("location:admin.php");
}

LINE 14 #SETUP THE QUERIES HERE FROM SESSION INFO

LINE 15 $sql1=mysql_query("SELECT * FROM admins WHERE username='$adminusr'"); ///connecting to the admin DB

LINE 16 $result1=mysql_fetch_array($sql1);

### OLD BAR INFO QUERY
$sql2=mysql_query("SELECT * FROM bars WHERE bar_id='$result1[bar_id]'"); ///connecting to the old bars DB
$result2=mysql_fetch_array($sql2);

###LIQUOR QUERIES
$sql3=mysql_query("SELECT * FROM inv_beer WHERE bar_id='$result1[bar_id]'"); ///connecting to the BEER INVENTORY DB
$beer_results=mysql_fetch_array($sql3);

Answer 1

What might be the issue is MySQL allows only one connection per user and you are trying to connect more than once which causes Access denied. Then your queries run fine because you already have one connection established. Without code though it is just a guess.

Answer 2

If these queries MUST run, then add an or die(); to the code like so:

$sql1=mysql_query("SELECT * FROM admins WHERE username='$adminusr'") or die('Critical error  on line #'. __LINE__ .'while trying to SELECT from admins table:<br>'. mysql_error());

That way you know exactly where the error is, what you were trying to do and the MySQL error description.

PS: If you are using string concatenation like above, I sure hope you are SQL escaping your data to prevent injection.

PPS: I recommend you use mysql_fetch_assoc() instead of _array() as it uses less memory because it doesn't waste time or memory populating keys 0,1,2,etc

Answer 3

If $adminusr isn't set the first time, no connection is made to the database. Put an exit() call after the header call.

After header is called, the script continues to run. That is why you get errors in the logs but don't notice them when using the site.