Is this script OK?

[DavidPr]

[PHP]<?php
$query = "SELECT viewed FROM $j where id='$file'";
$result = mysql_query($query);
while($row = mysql_fetch_array($result, MYSQL_ASSOC))
{
$viewed = $row['viewed'];
}

if ($viewed == '0')
{
$addone = '1';
}
else
{
$addone = $viewed + 1;
}

mysql_query("UPDATE $j SET viewed='$addone' WHERE id=$file");
?>[/PHP]

I want to know how many times an ad is viewed on my website. So I want the number stored in the row - $viewed - to increase by one each time the ad it's associated with is viewed. The default value is "0" so when the ad is viewed for the first time "0" is changed to "1" and then it increases by one each time it's viewed.

I just want to make sure that I have this right, because I wonder if sometimes the number isn't being increased by 2, 3 or more.

[Markus]

Looks fine to me.

The checking of whether the 'viewed' is 0 is pointless, though.

You can increment a number, instead of using '+ 1', by doing $var++ or ++$var.

[DavidPr]

The checking of whether the 'viewed' is 0 is pointless, though.

Yes, I guess it is.

You can increment a number, instead of using '+ 1', by doing $var++ or ++$var.

So all I really need to do is implement the update query.
[PHP]mysql_query("UPDATE $j SET viewed='$viewed+1' WHERE id=$file");[/PHP]How would I write the update query above to change the +1 to $var++?

[DavidPr]

How about this:
[PHP]function increment(&$viewed, $amount = 1)
{
$viewed = $viewed +$amount;
}[/PHP]

And then the update process:
[PHP]<?php
$query = "SELECT viewed FROM $j where id='$file'";
$result = mysql_query($query);
while($row = mysql_fetch_array($result, MYSQL_ASSOC))
{
$viewed = $row['viewed'];
}

increment($viewed);
$viewed = $viewed;

mysql_query("UPDATE $j SET viewed='$viewed' WHERE id=$file");
?>[/PHP]

By creating the increment function I can use it on other pages where I want to increase a database entry by one.

[Markus]

For simplicity's sake, you could just do (using $var++):

[php]
mysql_query("UPDATE $j SET viewed='$viewed++' WHERE id=$file");
[/php]

[DavidPr]

Yes, that does simplify things. Thank you.