My first request! Calculation with strings?

[Mathy]

$sql="SELECT points, gold, posts FROM users WHERE uname='" . Decrypt_Text($UN) . "'";
$r = mysql_query($sql, $conn);
if(mysql_affected_rows()>0) {
   $l = mysql_fetch_array($r);
   $sqla="UPDATE users SET points='" . $l["points"] + 2 . "', gold='" . $l["gold"] + 5 . "', posts='" . $l["posts"] + 1 . "' WHERE uname='" . Decrypt_Text($UN) . "'";
   echo $sqla;
}

 

The code above echoes "8' WHERE uname='Mathy'"

 

What did I do wrong here? Isn't it possible to add numbers to strings?

[kael.shipman]

What do you mean by add numbers to strings? If you want "this" + 1 to equal "this1", then you have to use the concatenator ".": "this".1 would equal "this1".  I would assume by your example, though, that you already know that, so please clarify your question.

[Mathy]

Yeah well, the $L array all contains numbers, so by $l['posts'] + 2 I mean the content of the $l['posts'] + 2 which would be 4 if $l['posts'] was 2. General calculation.

[sasa]

and what is wrong?

[akitchin]

my guess is that you're wrongly assuming what the $l array contains before running the calculations on it.  try running:

 

echo '<pre>'.print_r($l, TRUE);

 

just before the query to see what your values prior to the UPDATE are.

[Mathy]

Well, "echo $sqla;" echoes "8' WHERE uname='Mathy'".

 

So, if $l['points'], $l['gold'] and $l['posts'] was 1, it should instead echo:

 

"UPDATE users SET points='3', gold='6', posts='2' WHERE uname='Mathy'"

 

 

Why does it break it all up?

[Mathy]

my guess is that you're wrongly assuming what the $l array contains before running the calculations on it.  try running:

 

echo '<pre>'.print_r($l, TRUE);

 

just before the query to see what your values prior to the UPDATE are.

I know it contains something! I am almost sure. However, I should look at it, you are right. I will be replying shortly.

[redarrow]

<?php

$sql="SELECT `points`, `gold`, `posts` FROM `users` WHERE `uname`='" . Decrypt_Text($UN) . "'";

$r = mysql_query($sql, $conn);
if(mysql_affected_rows()>0) {
$l = mysql_fetch_array($r);

$po=$l["points"]+2;
$g=$l["gold"]+5;
$p=$l["posts"]+1;

$po=$_POST['po'];
$g=$_POST['g'];
$p=$_POST['p'];

$sqla="UPDATE `users` SET `points`='$po' AND `gold`='$g' AND `posts`='$p' WHERE `uname`='" . Decrypt_Text($UN) . "'";
$result=mysql_query($sqla);
echo $sqla;
}
?>

[sasa]

try

$sqla="UPDATE users SET points='" . ($l["points"] + 2) . "', gold='" . ($l["gold"] + 5) . "', posts='" . ($l["posts"] + 1) . "' WHERE uname='" . Decrypt_Text($UN) . "'";

i try to explain

PHP convert number to string and string to number, operator + except numbers and operator . except strings

old code say

"UPDATE users SET points='" . $l["points"] produce something like "UPDATE users SET points='5" type strimg

"UPDATE users SET points='5" + 2  convert "UPDATE users SET points='5" to number produce 0 and add 2 result is 2 (number)

2. "', gold='" . $l["gold"] => "2, gold='3" (string)

"2gold='3" + 5 (1st "2gold='3" to number => 2) 2 + 5 = 7

etc

 

[kael.shipman]

So it's a problem of parentheses and operator precedence, then. Good call, sasa. In that case you could either use the nice clean solution laid out by redarrow or just put your addition in parentheses and concatenate (like "UPDATE users set points = '".($l['points'] + 2)."', ....").