fluctuation of prices

[katarra]

I'm trying to write a script (cronjob) that will fluctuate the prices of all the items at a random level (+/- .03% or so), but when I ran this, it changed all the prices to match row #1 and wiped out everything else. (in other words, everything is now the same price as row #1)

 

Thanks for any help!

 

$query = $db->execute("select `price` from `items`");
$item = $query->fetchrow();
$price1 = ceil($item['price']*1.1);
$price2 = floor($item['price']*.9);
$newprice = mt_rand($price1, $price2);
$q = $db->execute("update `items` SET `price`=$newprice");

[DavidAM]

Hopefully, there is some unique ID for each row of the table.  You need to include that ID in the SELECT statement, loop through each row that is returned, and add a WHERE clause to the UPDATE.  Your current UPDATE has no WHERE clause so it is updating every row in the table with the same price.

[katarra]

Each has a unique ID, yeah. So, how would I include that in?

 

WHERE `id`=?" to the end of it?

 

I now have (just the rows that changed):

 

$query = $db->execute("select `id`, `price` from `items`");
$q = $db->execute("update `items`, `id` SET `price`=$newprice" );

[andrewgauger]

$query=$db->execute("select 'id','price' from 'items'");

$id=$item["id"];

$q=$db->execute("update 'items' SET 'price'=$newprice WHERE 'id'=$id");

[katarra]

Hmm... close.

 

It'll change the 1st row, but it doesn't change any of the following rows.

 

$query=$db->execute("select `id`,`price` from `items`");
$item = $query->fetchrow();
$id=$item["id"];
$price1 = ceil($item['price']*1.03);
$price2 = floor($item['price']*.97);
$newprice = mt_rand($price1, $price2);
$q=$db->execute("update `items` SET `price`=$newprice WHERE `id`=$id");

[andrewgauger]

$query=$db->execute("select `id`,`price` from `items`");
while($item = $query->fetchrow())
{
$id=$item["id"];
$price1 = ceil($item['price']*1.03);
$price2 = floor($item['price']*.97);
$newprice = mt_rand($price1, $price2);
$q=$db->execute("update `items` SET `price`=$newprice WHERE `id`=$id");
}