Nan

```
select
BINARY_DOUBLE_INFINITY INF,
BINARY_DOUBLE_NAN NAN,
greatest(BINARY_DOUBLE_INFINITY, BINARY_DOUBLE_NAN) GRE
from t;
INF NAN GRE
--- --- ---
Inf Nan Nan
```

Nan means not a number. It could be square root of -1, log of -1, 0/0, acos(1000), Inf-Inf, etc…

```
select
SQRT(-1d),
LN(-1d),
0/0d,
acos(1000d),
BINARY_DOUBLE_INFINITY-BINARY_DOUBLE_INFINITY
from t;
SQR LN- 00D ACO BIN
--- --- --- --- ---
Nan Nan Nan Nan Nan
```

According to the doc, it is greater than any value, inclusive positive infinity.

To check if a value is nan, it could be compared to BINARY_DOUBLE_NAN.

`where :z = BINARY_DOUBLE_NAN`

There is a function NANVL(:z, :y) which evaluates to :y when :z is equal Nan. if :z is not equal to Nan and :y is not null, then it evaluates to :z. NANVL evaluates to NULL when :z or :y is null.

```
select NANVL(1,null) from dual;
NANVL
------
[null]
```

You should ask Chuch Norris as he has counted to infinity, twice

but note than twice infinity is not bigger than infinity

select *

from dual

where binary_double_infinity*2

> binary_double_infinity;

No rows selected.

Anyway, I will ask him next time I see him on TV

“According to the doc, it [BINARY_DOUBLE_NAN] is greater than any value, inclusive positive infinity.”

it is not greater than itself:

SQL > select 1 from dual where BINARY_DOUBLE_NAN > BINARY_DOUBLE_NAN;

no rows selected

I can’t wait till Oracle will have implemented constants

Aleph-0, Aleph-1, …

Then, finally, continuum hypothesis will be trivially solved by

select 1 from dual where power(Aleph-0) = Aleph-omega

I can’t wait till Oracle will have implemented constants

Aleph-0, Aleph-1, …

Then, finally, continuum hypothesis will be trivially solved by

select 1 from dual where power(Aleph-0) = Aleph-omega

I can’t wait till Oracle will have implemented constants

Aleph-0, Aleph-1, …

Then, finally, continuum hypothesis will be trivially solved by

select 1 from dual where power(Aleph-0) = Aleph-omega

good point

and it is also not greater than BINARY_FLOAT_NAN and GREATEST(NULL,BINARY_DOUBLE_NAN) is NULL

I can’t wait until Oracle will have implemented the different infinite cardinals

Aleph-0, Aleph-1, …

Then, continuum hypothesis will be very elegantly decided by the query

select null

from dual

where power(2, ALEPH_0) = ALEPH_1

bets on the result are welcome

I can’t wait till Oracle will have implemented the different infinite cardinals

aleph-0, aleph-1, …

then, continuum hypothesis will very elegantly be decided by the query

select null

from dual

where power(2, ALEPH_0) = ALEPH_1

I learnt something new