Best structure for inventory database

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.

The problem I am facing is the following.

I have a table for my products, having an

id, name, price, quantity.

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:

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,-

So how do I model this in a sales record. Do I just create a concatenated record with the product id's comma separated.

Or is there another way do model this the right way.