MySQL Forums :: Newbie :: double join in update?

drop table if exists categories, products;
create table categories( category_id int unsigned primary key, category_name char(8)) engine=innodb;
insert into categories values (1,'food'),(2,'utensils');
create table products( 
  product_id int unsigned primary key, 
  category_id int unsigned, 
  product_name char(8),
  foreign key(category_id) references categories(category_id)
) engine=innodb;
insert into products values(1,1,'jam'),(2,2,'fork'),(3,1,'cereal'),(4,2,'knife');

select concat(c.category_name,':',p.product_name) as 'Category:Product'
from categories c
join products p using(category_id);
+------------------+
| Category:Product |
+------------------+
| food:jam         |
| food:cereal      |
| utensils:fork    |
| utensils:knife   |
+------------------+