[SOLVED] phpmath help please

[Jiraiya]

I looked online for tutorials on how to do this but i still don't understand im trying to use a if statement that if($row['gold'] >= 100) then it subtracts 100 from row gold and then adds 1 to row "potions" if anyone could help me or send a tutorial my way i would be very grateful.

[trq]

I assume you want to update a table with this info?

 

if ($row['gold'] >= 100) {
  $sql = "UPDATE tbl SET gold=gold-100, potions=potions+1 WHERE id = " . $row['id']
  // execute query
}

[Jiraiya]

yes thanks

 

[Jiraiya]

is there something wrong with the code it keeps coming up blank on my webpage.

 

<?php
$sql = mysql_query("SELECT * FROM users WHERE username = '$username'");
$row = mysql_fetch_array($sql);
if ($row['gold'] >= 100) {
  $sql = "UPDATE users SET gold=gold-100, potions=potions+1 WHERE username = '$username'") or die(mysql_error());
echo '<center>You have bought one health potion</center>';
}else{
echo '<center>You don't have enough gold. Come back when you get more.</center>';
}

?>

[lonewolf217]

look at the color coding of the code you posted.  the problem is this line

 

echo '<center>You don't have enough gold. Come back when you get more.</center>;

[Jiraiya]

i still dont see what is wrong with that line

[trq]

echo "<center>You don't have enough gold. Come back when you get more.</center>";

 

[Jiraiya]

i checked that and it still shows up white on the web browers

<?php
$sql = mysql_query("SELECT * FROM users WHERE username = '$username'");
$row = mysql_fetch_array($sql);
if ($row['gold'] >= 100) {
  $sql = "UPDATE users SET gold=gold-100, potions=potions+1 WHERE username = '$username'") or die(mysql_error();
echo "<center>You have bought one health potion.</center>";
}else{
echo "<center>You don't have enough gold. Come back when you getmore.</center>";
}
?>

[lonewolf217]

missing a closing ) on your die() statement here

<?php
  $sql = "UPDATE users SET gold=gold-100, potions=potions+1 WHERE username = '$username'") or die(mysql_error());
?>

 

turn on error reporting and you will see these errors

[Jiraiya]

this is the entire code so far i still didnt find any errors

 

<?php

mysql_connect("database", "username", "password") or die(mysql_error());
mysql_select_db("members") or die(mysql_error());

$sql = mysql_query("SELECT * FROM users WHERE username = '$username'");
$row = mysql_fetch_array($sql);
if ($row['gold'] >= 100) {
  $sql = "UPDATE users SET gold = gold-100, potions = potions+1 WHERE username = '$username'") or die(mysql_error());
echo "<center>You have bought one health potion.</center>";
}else{
echo "<center>You don't have enough gold. Come back when you getmore.</center>";
}

?>

[lonewolf217]

turn on error reporting in your PHP.ini so you can catch syntax errors.

 

you also have an extra parenthesis on your $sql line.  plus, you cannot run "or die()" when you are only assigning a text string.  that is used when you actually run the query

<?php
if ($row['gold'] >= 100) {
  $sql = "UPDATE users SET gold = gold-100, potions = potions+1 WHERE username = '$username'";
  $result = mysql_query($sql) or die(mysql_error());
  echo "<center>You have bought one health potion.</center>";
}else{
echo "<center>You don't have enough gold. Come back when you getmore.</center>";
}

 

again, turn on error reporting to catch these yourself

[manny]

i bellieve this should do it

<?php

mysql_connect("database", "username", "password") or die(mysql_error());
mysql_select_db("members") or die(mysql_error());

$sql = mysql_query("SELECT * FROM `users` WHERE `username` = '$username'");
$row = mysql_fetch_array($sql);
if ($row['gold'] >= 100) {
////Had error in this line
////  $sql = ("UPDATE users SET gold = gold-100, potions = potions+1 WHERE username = '$username'") or die(mysql_error());
$sql = ("UPDATE users SET `gold` = `gold`-100, `potions` = `potions`+1  WHERE `username` = '$username'") or die(mysql_error());
echo "<center>You have bought one health potion.</center>";
}else{
echo "<center>You don't have enough gold. Come back when you getmore.</center>";
}

?>

 

 

Let us know

[Jiraiya]

this code works better in the sense that now the web page shows up but the script still isnt doing anything it keeps displaying "You don't have enough gold. Come back when you getmore.

[premiso]

Do they have enough gold? I would print out the $row['gold'] in the else:

 

$currentGold = $row['gold'] - 100;
echo "<center>You have bought one health potion. You now have {$currentGold}.</center>";
}else{
echo "<center>You don't have enough gold, you currently have {$row['gold']}. Come back when you getmore.</center>";
}

 

And see what is displayed.

[Jiraiya]

it displayed

"You don't have enough gold, you currently have {$row['gold']}. Come back when you getmore."

[premiso]

Hmm. Not sure why it would have returned that...maybe it is an older version of PHP I do not know. This this instead:

 

$currentGold = $row['gold'] - 100;
echo "<center>You have bought one health potion. You now have " . $currentGold . ".</center>";
}else{
echo "<center>You don't have enough gold, you currently have " . $row['gold'] . ". Come back when you getmore.</center>";
}

 

See if that produces a number. I have a hunch that it showed the $row['gold'] portion maybe because it is not defined...no clue....it seems there maybe an issue on your server ???

[Jiraiya]

You don't have enough gold, you currently have . Come back when you getmore.

thats what is displayed

[premiso]

<?php

mysql_connect("database", "username", "password") or die(mysql_error());
mysql_select_db("members") or die(mysql_error());

$sql = mysql_query("SELECT * FROM `users` WHERE `username` = '$username'");
if (mysql_num_rows($sql) > 0) {
    $row = mysql_fetch_array($sql);
    if ($row['gold'] >= 100) {
     ////Had error in this line
     ////  $sql = ("UPDATE users SET gold = gold-100, potions = potions+1 WHERE username = '$username'") or die(mysql_error());
       $sql = ("UPDATE users SET `gold` = `gold`-100, `potions` = `potions`+1  WHERE `username` = '$username'") or die(mysql_error());
        echo "<center>You have bought one health potion.</center>";
    }else{
        echo "<center>You don't have enough gold. Come back when you getmore.</center>";
    }
}else {
    echo "No rows were returned by the SQL. Username entered was " . $username;
}
?>

 

Where does $username come from? Try the above, my bet is that $username will not display. You need to assign $username a value some how whether from $_POST/$_GET/$_SESSION, it seems like you are assuming register_globals is turned on, which it is not and this is causing the problem.

[Jiraiya]

No rows were returned by the SQL. Username entered was

is what it displayed

[Jiraiya]

ok it now displays "You have bought one health potion."

but its not updating the database

$sql = mysql_query("SELECT * FROM `users` WHERE `username` = '$username'");
$row = mysql_fetch_array($sql);
if ($row['gold'] >= 100) {
$sql = ("UPDATE users SET `gold` = `gold`-100, `potions` = `potions`+ 1  WHERE `username` = '$username'") or die(mysql_error());
echo "<center>You have bought one health potion.</center>";
}else{
echo "<center>You don't have enough gold. Come back when you getmore.</center>";
}

[manny]

Do they have enough gold? I would print out the $row['gold'] in the else:

 

$currentGold = $row['gold'] - 100;
echo "<center>You have bought one health potion. You now have {$currentGold}.</center>";
}else{
echo "<center>You don't have enough gold, you currently have {$row['gold']}. Come back when you getmore.</center>";
}

 

And see what is displayed.

correction on

 

echo "<center>You don't have enough gold, you currently have ". $row['gold'].". Come back when you get more.</center>";

 

goahead and see if it shows or what it shows

[Jiraiya]

 

 

ok it now displays "You have bought one health potion."

but its not updating the database

Code: [select]

$sql = mysql_query("SELECT * FROM `users` WHERE `username` = '$username'");

$row = mysql_fetch_array($sql);

if ($row['gold'] >= 100) {

$sql = ("UPDATE users SET `gold` = `gold`-100, `potions` = `potions`+ 1  WHERE `username` = '$username'") or die(mysql_error());

echo "<center>You have bought one health potion.</center>";

}else{

echo "<center>You don't have enough gold. Come back when you getmore.</center>";

}

 

[manny]

wow i totally forgot

 

change

$sql = ("UPDATE users SET `gold` = `gold`-100, `potions` = `potions`+ 1  WHERE `username` = '$username'") or die(mysql_error());

 

to

change

$sql = ("UPDATE users SET `gold` = (`gold`-100), `potions` = (`potions`+ 1)  WHERE `username` = '$username'") or die(mysql_error());

[premiso]

 $sql = mysql_query("UPDATE users SET `gold` = `gold`-100, `potions` = `potions`+ 1  WHERE `username` = '$username'") or die(mysql_error());

 

Will get it to update the database.

[manny]

True but the other way will let you run more complex formulas

better to get use to a better way

 

Finally SOLVED