I have attempted a few methods to update a column inside a mySQL database table from another table but am not getting any luck.

I just read somewhere that version 3.5.2 doesn't support multi-table updates and that i require a code-based solution - is the fact that correct?

Otherwise can anybody point me within the right direction using sql?

UPDATE products SET products_ordered = (
    SELECT SUM(products_quantity) 
    FROM orders_products 
    WHERE products_id = products.products_id
);

or:

Create temporary table my_temp_table
as
SELECT products_id, SUM(products_quantity) as total 
FROM orders_products 
GROUP BY products_id 

UPDATE products, my_temp_table
SET products.products_ordered = my_temp_table.total 
WHERE products.products_id = my_temp_table.products_id

When I did previously use MySQL that didn't support either subqueries or multi-table updates, I made use of a trick to complete what you are explaining. Operate a query whose answers are themselves SQL claims, after which save the output and run that being an SQL script.

SELECT CONCAT( 
  'UPDATE products SET products_ordered = ', 
   SUM(products_quantity), 
  ' WHERE product_id = ', products_id, ';') AS sql_statement
FROM orders_products
GROUP BY products_id;

Incidentally, there's no such version MySQL 3.5.x so far as I understand. I believe you might have reported that wrong. Otherwise you are using another product for example mSQL.

Edit: I didn't remember to include a semicolon in to the SQL statement produced through the query above.

Multi-table updates aren't support in MySQL <= 4..4 I'd recommend to improve your server to MySQL 5..xx