php mysql query returns nothing, phpmyadmin with same query returns result

Question

I am trying to delete a file or copy a row into a new table, depending on a $_GET. The $_GET works fine, and I'm not including all the code, I know it isn't relevant. The table copy works, but the select statement that gets called when the $_GET is a different value returns nothing, except when I copy the query directly into phpmyadmin.

Base code:

$pID = $_GET['pID'];

$con = mysqli_connect("...","...","...","...");

The following works:

$query = 'INSERT INTO `photos` (`id`, `photo1`, `photo2`, `demographic_id`)
SELECT `id`, `photo1`, `photo2`, `demographic_id`
FROM `photos_queue`
WHERE `photos_queue`.`demographic_id` = '.$pID;

mysqli_query($con, $query);

This does not:

$query = 'SELECT `photo1` FROM `photos_queue` WHERE `demographic_id` = '.$pID;
$result = mysqli_query($con, $query);
print($result);
unlink($result);

I've printed $query and the value of it is valid; I can copy it directly into phpmyadmin and it will work fine.

have you echoed out mysqli_error() to see if it is erroring out? — Patrick Evans
– Patrick Evans, Commented Oct 5, 2013 at 0:47
You seem to have forgotten to call mysqli_fetch_XXX() to get the row from the query. — Barmar
– Barmar, Commented Oct 5, 2013 at 0:50
user2722375: A good idiom that is seen a lot when creating these connections is $con = mysqli_connect("...","...","...","...") or die(mysqli_error());. Obviously, the call to die() kills the script, so I usually use it for debugging... but I think it'd help you here. — Thomas Kelley
– Thomas Kelley, Commented Oct 5, 2013 at 0:50

Barmar · Accepted Answer · 2013-10-05 00:52:08Z

1

mysqli_query() doesn't return the table data, it just returns a resource that can be used to fetch it. You need to do:

$result = mysqli_query($con, $query) or die (mysqli_error($con));
$row = mysqli_fetch_assoc($result);
$filename = $row['photo1'];
print($filename);
unlink($filename);

answered Oct 5, 2013 at 0:52

Barmar

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8 Comments

user2722375 Over a year ago

Aha, that's it! I looked at another file that was giving me data just fine, but didn't notice I had skipped the mysqli_fetch_assoc/mysqli_fetch_row part. Thank you!

user2722375 Over a year ago

Unfortunately it still doesn't delete the file. The value of photo1 is "foldername/filename.jpg". I tried prepending "mysite.com" so the value of $filename would be "mysite.com/foldername/filename.jpg" but it still doesn't delete.

Barmar Over a year ago

That's a totally unrelated problem. I don't know why you would prepend the domain name, filenames are not URLs. If the file is outside the document root, you need to prepend that path. Find the script that creates the file, and see where it puts them.

user2722375 Over a year ago

"foldername/filename.jpg" is the value I use as the src of an <img> and it works fine. It's inside of a folder called "foldername" which is in the root folder.

Barmar Over a year ago

Maybe prepend $_SERVER['DOCUMENT_ROOT']? I came here to help you with SQL, I can't really guess the layout of your webserver.

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user2812509 · Accepted Answer · 2013-10-06 20:04:30Z

0

($row = mysqli_fetch_array($result)

This should be placed after,

$result = mysqli_query($con, $query);

answered Oct 6, 2013 at 20:04

user2812509

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