[PHP] passing variables to a sql statement

[jennifer]

hi, i'm hoping someone can help me out here - im trying to pass a variable from a 
string in the href tag, however my sql breaks when i put a var in the statment.
when i replace $foo with a number, the page works fine. can someone please tell me 
what im doing wrong?

here is the error i get:

Warning: Supplied argument is not a valid MySQL result resource in 
/home/villany2k1/www.villany2k1.com/htdocs/projects/projects_descrip.php on line 11



here is my code:

<?php
$hostName="localhost";
$userName="xxxx";
$password="xxxx";
$database= "projects";
$tableName="project_descrip";

$descripQuery = "SELECT descrip from project_descrip where rowid=$foo";
mysql_connect($hostName, $userName, $password);
$descripResult = mysql_db_query($database,$descripQuery);
   while($row = mysql_fetch_object($descripResult)){

$foo = $row->descrip;

echo("<font face=verdana size=1>");
echo("<a href='projects_descrip.php?rowid=$foobar'>" . "$foo</a>" . " | ");
echo("</font>");

  }


?>

thanks in advance, 
jennifer