I want to merge the field "price" from the table "products" into the field "price" in the table "products_description". Both tables has "products_id" that match.
Can't really get my head around it.
UPDATE products_description pd INNER JOIN products p ON p.productid = pd.productid SET pd.price = p.price;
That will copy the price from table products into products_description! Although it may not be 100% apparent this is what you want.