Adding and updating numbers in a database

[supanoob]

well, i am trying to do a gym for my Browser based game. now i know what i want to do i just dont know where to start.

now the basic idea is i want to add a random number between 0.1 and 0.7 to the number that is already in the database (which to start with is 10) then i want it to update it straight away. any advice on how to do this?

[Orio]

Something like this?

<?php
$sql="SELECT num FROM `table` WHERE user='$user'";
$result=mysql_query($sql);
$the_num=mysql_result($result, 0);
$rand=rand(0,7);
$rand=$rand/10;
$update=$the_num+$rand;
$sql2="UPDATE `table` SET num='$update' WHERE user='$user'";
if(mysql_query($sql2)){
echo("updated");
}
?>

Orio.

[supanoob]

Warning: mysql_result(): supplied argument is not a valid MySQL result resource in /home/content/A/r/c/ArchAngel390/html/game/power.php on line 24

i get that error :S

this is the code after i changed what i thought needed to be changed

[code]<?php
session_start();
require_once('header.php');

if (!$_SESSION['valid_user'])

{ echo 'you are not logged in';

die();
}
$user=$_SESSION['valid_user'];

$query="select playerid, user, email, gold, fatigue, maxfat, power, speed, dex, intel, health, maxhealth, gender from players where user='$user'";
$result=mysql_query($query);
if (!$result)
{
die (mysql_error());
}

$num_rows=mysql_num_rows($result);

$sql="SELECT power FROM $tablename WHERE user='$user'";
$result=mysql_query($sql);
$power=mysql_result($result, 0);
$rand=rand(0,7);
$rand=$rand/10;
$update=$the_num+$rand;
$sql2="UPDATE `table` SET num='$update' WHERE user='$user'";
if(mysql_query($sql2))

{
echo "you gained $rand power";

die();
}

{
echo "Power is now $power";

die();
}
?>[/code]

[.josh]

so which one is line 24?

i think it might be here:

$sql2="UPDATE `table` SET num='$update' WHERE user='$user'";

shouldn't 'table' actually be your table name instead of 'table' ?

i see earlier on in the code you have a table named players and then after that you refer to your table name as $tablename

[Brandon Jaeger]

[code]$result=mysql_query($query);
if (!$result)
{
die (mysql_error());
}[/code]
A slight optimization:
[code]$result=mysql_query($query) or die(mysql_error());[/code]

[supanoob]

thanks i will let you know how i get on :D

[supanoob]

well, good news it works kinda :P

i click the train button. and it adds to the power. but evey time it does so it resets the power to 1 instead of adding it to the 10 that is alread in there.

for example i click it once, and it added .2 to my power. so i went and checked the database to make sure i added and the power was then 1.2. so i went and clicked again and gained .7 and check the database and it was 1.7 instead of the 10.9 i wanted it too be :(