Re: Why does this not work ?

On 8/03/2014, at 8:05 AM, Roelof Wobben wrote:
> I have this problem.

This sounds uncommonly like homework.
> 
> Write a query against the item and inventory records that returns the inventory level for an item when you only know the item name. 
> 
> I have this facts:
> 
> customer(wobben, musselkanaal, aaa).
> 
> customer(ankone, hengelo, bbb).
> 
> customer("de jong", haaksbergen, ccc). 

Why all the blank lines?
Why is there no comment saying which argument
stands for what?
Why do the first two facts use atoms for whatever
argument 1 is, while the last fact uses a string?

> item(1, pan, 0). 
> item(2, beker, 1). 

Why is there no comment saying which argument
means what?
> 
> inventaris( 1, 12). 
> inventaris( 2, 10).

Why is there no comment .....
> 
> So I tried this:
> 
> inventaris(X,Y),item(X,pan,0).

I pasted your code into a file and tried it,
and it worked.  Next time, I think you had
better show us _exactly_ what you did.