PHP does not add to MYSQL

Question

I have the following code which updates a field in a database table to add 1 to it. The ID should have a variable being posted to it. Can anyone see where this is going wrong?

EDIT: Sorry, I completely forgot to mention the actual problem. The database is not updating the field.

<?php
$con=mysqli_connect("localhost","**","***","***");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

mysqli_query($con,"UPDATE base SET thumbdown = thumbdown + 1 WHERE id = $_POST['id']");

mysqli_close($con);
?>

The query looks fine. Just a wild guess, but could you please print out the $_POST['id'] variable? My guess is it is either not set, or not set to an integer value you are expecting it to be set to. — David Fleeman
– David Fleeman, Commented Nov 7, 2013 at 18:27
@LorenzMeyer This is what is baffling me. The variable is set and I have also tried printing it as a variable as David said. — googleyberry
– googleyberry, Commented Nov 7, 2013 at 18:32

Funk Forty Niner · Accepted Answer · 2013-11-07 19:19:50Z

3

You wont get the $_POST['id'] parsed in to the string correctly as it is an array. You must enclose it in braces:

"UPDATE base SET thumbdown = thumbdown + 1 WHERE id = '{$_POST['id']}'"

But remember (always!) to escape the variable first:

$id = mysqli_real_escape_string($_POST['id']);
mysqli_query($con,"UPDATE base SET thumbdown = thumbdown + 1 WHERE id = '{$id}'");

edited Nov 7, 2013 at 19:19

Funk Forty Niner

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answered Nov 7, 2013 at 18:32

Maciej Sz

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11 Comments

Maciej Sz Over a year ago

How do you know if the id field in the db table is an integer? Did I miss something?

googleyberry Over a year ago

I have it set to an integer. I have just tried this code, and it doesnt seem to be working either?

Maciej Sz Over a year ago

Then you must provide more detail. What is the output? Are there any errors displayed?

googleyberry Over a year ago

I have a system that is posting to the php script. I have confirmed that it is sending the variable 'id' correctly, for example, I can confirm that it sends over a '4' into the ID variable. There are no visible errors. If I hardcode a number into the script then it works just fine, but the issue seems to come from something to do with the variable.

Lorenz Meyer Over a year ago

@maciej There are no quotes around it in the query.

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