Question

I’m trying to create a variable which is dependent on some information from the database. I’m trying to generate a $path variable which stores a path, depending on what information is recovered from the database.

$linkid = mysql_connect('localhost','user','password');
mysql_select_db("table", $linkid);
$variable = "00001";
$groupID = null;
$temp = mysql_query("SELECT groupID FROM table WHERE memberID='$variable'", $linkid);

while ($row = mysql_fetch_row($temp)){
    global $groupID;
    foreach ($row as $field){
        $groupID = $field;
    }
}

....

$path = "C:\WAMP\www\project\\" . $groupID;
$dir_handle = @opendir($path) or die('Unable to open $path');

The idea behind this is that $variable is set before the PHP is run, however it’s set to 00001 for testing. The ideal situation is that $path should equal C:\WAMP\www\project\00001\. Currently, when I echo back the $path all I get is the original path without the $groupID added to the end.

I also receive the message “mysql_fetch_row() expects parameter 1 to be resource” but I’ve used this method for retrieving information before and it worked just fine, and I set up my table in the same way so I don’t think the issue is there.

I have a feeling I’m missing something obvious, so any help is appreciated. It’s not for an assignment or anything school related (just trying stuff out to learn more) so knock yourselves out with correcting it and explaining why 🙂

In addition, only one memberID will ever be a match to the $variable, so if there’s an alternative way to fetch it I’d appreciate knowing.

Oh, and I know my variable names are shocking but they’re only that on here, on my actual code they’re different so no criticism please :p

EDIT: The SQL query is correct, after following BT634’s advice and when running it on phpMyAdmin I get the groupID I want and expect.

Answer 1

First of all, you’re not specifying what database to connect to in your connection – you’re specifying what table. You might also want to check how many rows your query is returning:

$temp = mysql_query("SELECT groupID FROM table WHERE memberID='$variable'", $linkid);
echo mysql_num_rows($temp);

If it’s still complaining about $temp not being a valid resource, change your MySQL connection code to:

// Establish connection
$con = mysql_connect("localhost","peter","abc123");
if (!$con) die('Could not connect: ' . mysql_error());
mysql_select_db("my_db", $con);

// Make your query
$result = mysql_query("SELECT groupID FROM table WHERE memberID='$variable'");

// Find out what the value of the query is (i.e. what object/resource it is)
var_dump($result);

---

Once you know that MySQL is returning valid data, extract the values you want. You don’t have to use globals:

while ($row = mysql_fetch_row($temp)){
    $groupId = $row[0];
}

// Use $groupId however you please...

One thing to bear in mind is that mysql_fetch_row will return

array
(
   0 => '...'
)

Whilst mysql_fetch_assoc will return:

array
(
   'groupId' => '...'
)