i dont know whuts wrong.

PunkGo

theres no errors showing up but my code wont do whut i want it to...when i login succesfully, and goto this code im about to show u, i want it to subtract 4 points from my username's coulmn.. heres the code..

<?php

mysql_connect("localhost", "punkgo_punkgo", "******")
or die(mysql_error());

mysql_select_db("punkgo_test")
or die(mysql_error());

$username = $_POST['username'];
$password = $_POST['password'];
$ring = $_POST['costofring'];
$cost = 4;
$points = mysql_query("SELECT points FROM user WHERE username='$username'")
or die(mysql_error());

if($points > $cost){
mysql_query("update user set points=points-$cost where username=$username");
}
else {
echo 'wrong';
}
?>

but it keeps showing up as 'wrong' on the page...any suggestions?

drawmack

update user set points=points-$cost where username=$username

okay I can help with this.

1) parenthesize all math - it technically isn't necessary but aids in readability and can sometimes add in execution speed as well.

2) unless username is a numeric field you need some quotes.

3) as a matter of style is helps set appart sql commands from field/table names it you use all caps for them.

so our new query is this

UPDATE user SET  point = (points-$cost) WHERE username="$username"

4) in php is it a good idea to feed you sql into a variable so you can echo it out on a failure and see what is happening more clearly.

So the PHP is this

<?php
$sql = "UPDATE user SET  point = (points-$cost) WHERE username=\"$username\"";
@mysql_query($sql) or die(mysql_errno() . ": " . mysql_error() . "<br />" . $sql);
?>

PunkGo

hmm..still says wrong..heres my new code

<?php

mysql_connect("localhost", "punkgo_punkgo", "****")
or die(mysql_error());

mysql_select_db("punkgo_test")
or die(mysql_error());

$username = $_POST['username'];
$password = $_POST['password'];
$ring = $_POST['costofring'];
$cost = 4;
$points = mysql_query("SELECT points FROM user WHERE username='$username'")
or die(mysql_error());

if($points > $cost){
$sql = "UPDATE user SET points = (points-$cost) WHERE username=\"$username\""; 
@mysql_query($sql) or die(mysql_errno() . ": " . mysql_error() . "<br />" . $sql); 
}
else {
echo 'wrong';
}
?>

....any suggestions?

LordShryku

Are you sure $points > $cost? According to your script, it's not even getting to the update if it's just saying "wrong"...

Weedpacket

If you echoed $points you'd find that it's a resource - the result set returned by MySQL. You still need to get the points out of that with something like mysql_result.

Of course, this whole exercise can be done with a single query. Replace the SELECT with

UPDATE user
SET points = (points-$cost)
WHERE username='$username'
    AND $points>$cost

And you can tell if it happened or not by asking mysql_affected_rows(); it's "wrong" if it returns 0.

ramkumar_unknow

Originally posted by Weedpacket
If you echoed $points you'd find that it's a resource - the result set returned by MySQL. You still need to get the points out of that with something like mysql_result.

Of course, this whole exercise can be done with a single query. Replace the SELECT with
UPDATE user
SET points = (points-$cost)
WHERE username='$username'
    AND $points>$cost
And you can tell if it happened or not by asking mysql_affected_rows(); it's "wrong" if it returns 0. [/B]

you have say $points["points"] instead of $points in if statement