lnnvl [Oracle SQL]

... where lnnvl(condition)...

create table lnnvl_ex (
  a number,
  b number
);

insert into lnnvl_ex values (null, null);
insert into lnnvl_ex values (null,    1);
insert into lnnvl_ex values (   2,    2);
insert into lnnvl_ex values (   3, null);
insert into lnnvl_ex values (   4,    5);

select * from lnnvl_ex where a=b;

         A          B
---------- ----------
         2          2

select * from lnnvl_ex where lnnvl(a=b);

         A          B
---------- ----------

                    1
         3
         4          5