You will have to combine the 3 tables by joining or mapping in the relevant information from table B and C into table A (ApplyMap()).
Then the calculation becomes straight forward. with a few exceptions, such as Exists and Lookup,LOAD statements can only reference fields from one table at a time. Presumably you have some common key to associate the records in one tables with the corresponding records in the other tables.
Thanks for coming back to me. So my tables are joined thus:
Table A is the primary source of data, and Tables B and C are supplementary data fields.
I have 4 fields that are mirrored across each table (site number, customer number, order number, order release number), allowing Qlik to create its own unique key, and so the records align properly when I pull data together into the visuals.
Given this additional information, do you think ApplyMap is the right way to go? I will be honest I hadn't heard of it until you mentioned it.
Was I on the wrong track with Resident function?
Thanks for helping so quickly! Cheers. Giles