Globally Updating a table

[Rulkster]

Im trying to update a field in my table (specifically the price field) where i choose the price i wish to change, and wherever there is an instance of that price in a table it will change to the new price. This is what i have so far, but it is not working:

(for example, ill just hard code the variables)
$oldprice = 9.99
$newprice = 5.99

here is my sql statement:

$sql = "update product_table
set

product_price=$newprice

where product_price = $oldprice
";
$result = @($sql,$db)or die("Couldn't execute query.");

i echo my $sql statement and it looks like this:

update product_table set product_price=5.99 where product_price = 9.99

But all instances of the 9.99 price still remain..
What am i doing wrong???

ps, if it matters the field product_price is of float type 5,2

[Sxooter]

Have you run this query by hand from the mysql command line tool? If so, what errors if any did you get?

In Postgresql I had to cast my values like so:

update test set price=5.99 where price=9.99::numeric;

[Lars_Berg]

Yes it does matter. Use decimal(5,2) instead