This will
return first non-null value.
Syntax: coalesce (value1, value2,
value3 … valuen)
Ex:
SQL> select coalesce(1,2,3), coalesce(null,2,null,5) from dual;
COALESCE(1,2,3)
COALESCE(NULL,2,NULL,5)
------------------- -------------------------------
1 2
