Every day I will download a "product inventory" list from an third party source, the list is in the format like this:
| Product Code | Product Name | Quantity |
|---|---|---|
| 1 | Apple | 100 |
| 2 | Pear | 200 |
| 3 | Banana | 150 |
| 4 | Grape | 400 |
However, not all product shows up everyday. In the next day the report may look like this:
| Product Code | Product Name | Quantity |
|---|---|---|
| 1 | Apple | 120 |
| 3 | Banana | 200 |
| 4 | Grape | 320 |
| 5 | Kiwi | 80 |
And I want to be able to join these two tables and build an "product movement" report like the following
| Product Code | Product Name | Delta |
|---|---|---|
| 1 | Apple | +20 |
| 2 | Pear | -200 |
| 3 | Banana | +50 |
| 4 | Grape | -80 |
| 5 | Kiwi | +80 |
Could someone please give me some pointers on how to achieve this?