What is the best way to represent 'N' no. of Products in 'M' no. of warehouses with the quantities included
<p>I want to make relationship between Product entity and Warehouse(location) Entity as you can see in the picture below.</p>

<p>But the problem is the Quantity since the quantity differs in each warehouse and for each product i am not sure if its correct way since in most of the class diagrams for eg. doctrine2.5 there is no mapping class diagram simply annotation would do. </p>

<p>I know i can add extra column in the product entity but what if there are many warehouses i have not seen any practical with many warehouses usually there are large warehouses(space).</p>

<p>What is the best way to represent 'N' no. of Products in 'M' no. of warehouses with the quantities included.</p>

<p><a href="http://i.stack.imgur.com/q37jc.jpg" rel="nofollow">My ER Diagram</a></p>