Which query works in both SQL Server and Oracle?

Question

I am searching for a SELECT query that works in both SQL Server and Oracle. It does not matter what it selects or what the result is, but it cannot depend on the database contents.

This sounds like a simple thing to do, but I cannot come up with an example.

First I thought of SELECT 0, but Oracle needs FROM dual which SQL Server does not support. Then I tried SELECT * FROM INFORMATION_SCHEMA.TABLES, but Oracle does not have those...

Edit: this question arose trying to check whether some SQL Server linked servers are reachable. But I think it is very interesting by itself.

Answer 1

On rextester, the following works for both SQL Server and Oracle:

select count(*)
from sys.all_objects;

There may be a handful of other sys tables that this would work for.

EDIT:

I'm going to echo Jeroen's comment. If you want the same result as well, then add a clause that filters out all rows:

select count(*) as always_zero
from sys.all_objects
where 1 = 0;