Oracle 18c

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create table t (i int null)
insert into t values (0)
1 rows affected

insert into t values (1)
1 rows affected

insert into t values (null)
1 rows affected

select t.i, case when t.i <> NULL then 'true' else 'false' end as "Not Equal to NULL"
FROM t


I
Not Equal to NULL


0
false

1
false

null
false