title: Best structure for inventory database
body: <p>I want to create a small database for my inventory but I have some problems on picking a structure. The inventory will be updated daily at the end of the day.</p>
  
  <p>The problem I am facing is the following.</p>
  
  <p>I have a table for my products, having an </p>
  
  <pre><code>id, name, price, quantity.
  </code></pre>
  
  <p>Now I have another table for my sales, but there is my problem. What kind of fields do I need to have. At the end of the day I want to store a record like this:</p>
  
  <pre><code>20       product_x       $ 5,00         $ 100,-
  20       product_y       $ 5,00         $ 100,-
  20       product_z       $ 5,00         $ 100,-
  20       product_a       $ 5,00         $ 100,-
  -------------------------------------------------
                                          $ 400,-
  </code></pre>
  
  <p>So how do I model this in a sales record. Do I just create a concatenated record with the product id's comma separated. </p>
  
  <p>Or is there another way do model this the right way.</p>