Select  UNIQUE CASE when LENGTH(CORPORATE_ID) <6  then  SUBSTR('000000'||TRIM(BOTH FROM CORPORATE_ID ),CHARACTER_LENGTH('000000'||TRIM(BOTH FROM  CORPORATE_ID))-5+1,5)||
SUBSTR('000000'||TRIM(BOTH FROM LOCATION_ID),CHARACTER_LENGTH('000000'||TRIM(BOTH FROM LOCATION_ID))-6+1,6) else BILLING_ID  END AS BILLING_ID,
LOCATION_NM from TABLES.BILL_LOCATION

--Example of utilizing data transformation/concatenation of two source fields to match primary key field (example - CORP_ID of 1234 & LOCATION_ID of  12345 would have a BILLING_ID of 01234012345)