Add unique identifier during load

[#1]

I'm trying to add an unique identifier to each record during load. Since I'm combining various data source I need a variable to keep track of this identifier. Below the script I have without the identifier. So I need a way to update QVId during the load. Again your help is very much appreciated!

COMPANIES:                                                                                                                                                                                                                                                                                                                                          ///Create table containg file names for loop, companies and qualifiers
LOAD * INLINE
   [COMPANY
    FUEL
    GAS];

DATABASES:
LOAD * INLINE
          [DATABASE
           CONFIRMED
           HISTORY
           ACTIVITY];
                     
LET QVId = 0;

LET n = NOOFROWS('COMPANIES');
FOR i = 1 TO n
LET vC = FIELDVALUE('COMPANY',i);

$(vC)ACTIVITY:

          LET m = NOOFROWS('DATABASES');
          FOR j = 1 TO m
          LET vDB = FIELDVALUE('DATABASE',j);

LOAD
  UNIQUE IDENTIFIER AS QVId,
          *
FROM
$(vC)_DC_$(vDB).QVD (QVD)
WHERE NOT EXISTS('KEYCoHiAc', Source & TruckId & ShiftDate & ShiftNb & TripSequenceNb & SequenceNb & SubSequenceNb & Activity & SiteId & StorageId & MaterialId);

LET QvId = PEEK('QVId');

NEXT

STORE $(vC)ACTIVITY INTO $(vC)ACTIVITY.QVD (QVD);
DROP TABLE $(vC)ACTIVITY;

NEXT

DROP TABLES COMPANIES, DATABASES;