Well, you could just sit down and design your own database, then try to implement it.

Here is a medium complex database you could try designing: Inventory control

Table of Items, table of bins, table of warehouses, table of bin_items, table of transfers

Rules

• Each item can exist in multiple bins
• Each bin can contain multiple items
• Each warehouse has multiple bins
• Each transfer can only transfer items out of the source bin that are actually IN the source bin.

Schemes

• Items: ID, NAME, DESCRIPTION
• Bin_items: ID, ITEM_ID, BIN_ID, QTY
• Bins: ID, LOCATION_CODE, WAREHOUSE_ID
• Warehouses: ID, NAME, ADDRESS, PHONE_NUMBER
• Transfers: ID, SRC_BIN_ID, DST_BIN_ID, ITEM_ID, COMPLETE (BOOLEAN)

Views

• See all items, with their qtys, wherever they are
• See only a certain item, wherever it is
• See all items in a certain bin
• See all items in a certain warehouse
• See all transfers for a certain item
• See all transfers within the past week
• See all transfers per warehouse
• See all transfers per bin

Actions

The user should be able to:

• Add / Edit / Deactivate Items
• Add / Edit Bins
• Add / Edit Warehouses
• Easily add items to a bin from nowhere (inventory receiving)
• Create transfers for items from one bin to another
• Complete the transfers (modify/add the 'complete' checkbox for the transfer). This action should fire UPDATE events which update the corresponding bins.

And that took me 10 min to think up and type. I'm certain you could come up with a lot more. :)

[and no, this is not a request for code. We have a way better inventory control program already.]

Have fun!