2

It will return 0 rows as 1 will never be ewual to 2

no rows selected

It will return 0 rows....since condition in where clause 
will fail as 1 is not equal to 2

indeed it will return o rows, but the goal behind is to 
create a new table t2 as select * from t1 where 1=2, where 
just the structure of table t1 will be copied without 
copying data from table t1.

In Oracle 10g :
---------------

no rows selected.


E.g:
----

SQL> SELECT * FROM job;

    EMPNO JOBTITLE
--------- --------------------
        1 Tester
        2 Accountant
        3 Developer
        4 COder
        5 Director
        6 Mediator
        7 Proffessor
        8 Programmer
        9 Developer

9 rows selected.

SQL> SELECT * FROM job WHERE 1=2;

no rows selected.