Hi
Check this if you want unique identifiers you can use the following ways.
Creat a sequence and use the same as a column by
Select colA, colB, colC...,(SELECT seq.NEXTVAL FROM DUMMY) as colZ
from TableAB
where colA = 'A1';
If the uniqueness is a combination of columns then you can try the
ROW_NUMBER() over (partition by colA,colC order by colA.colC)