You can leave all tables separate (though this may not e the best solution), as long as you create one or more decent keys between their rows. Include a date and an order number if possible. QlikView enjoys grabbing fields from different live tables and putting them together in an apparently single report object.
The trick is in designing a good connection between the different sources. What selection fields do you want to present in your BO report? Do users get period fields or a timeline? Item is a good candidate to be included in these keys. What other selections need to flow through the data model?
well, I'll start from the back here:
=> Once you have a single table with the new information from both sources, appending that to a historization_table is quite easy:
a) load original historization_table
b) load new data
c) append new data to historization_table (you might have to check through a key that you don't append the same records twice and thus create duplicates)
d) store as a qvd
First, however, you need to make one table from the two sources, which is probably the more difficult part:
=> It's hare (impossible) to link or join through a field you don't have, opbviously.
Can you post two small sample files to visualize how your source_data looks and how you would like to combine it?
I would combine the records from both order systems into a single table, but conform the table structures so that customer name, item no, etc all have the same field name (use LOAD .. As .. ).
Are you calculating the BO amounts in the QV document? Either way, I would include the BO amount on the already loaded order lines and would set a BO flag on each order that has gone onto back order. Then you can select the flag (BO = yes) and the item name (xyz), and you will only see the customers with back orders for that item. Clear the BO flag, and you will see all customers who ordered that item.