GET value and execute it as query

[hisham777]

my opolagies if this is considered as a dublicated thread.

Q is this code is to get the category id from a table and display it
as a link.

while ($row = mysql_fetch_assoc($result)) {
echo '<a href="Displaycategory.php?category_id='
. '">'
. $row['category_id']  
. '</a>' . '<br />'; 

this is the code to GET the product id an fatch the rows from a table
where the product id = Whats in GET

$result = mysql_query("select * from products where category_id = '". $_GET['category_id'] ."'");

if (!$result) {
die('Invalid query: ' . mysql_error());
}

if(mysql_num_rows($result) != 0)
{
while($rows = mysql_fetch_assoc($result)) {
echo $rows['description'] .'<br />';
}
}
else
{
echo "no results";
} 

after testing the code the 1st one working fin it get the category id
from the table and display it as a link.
but when its clicked it execute the secound script but it does nothing
-there are few records in the tables.

is this the write method to use it as a query.?
help please.