There is no special SQL statements to calculate expressions. But you can use the "SELECT expression FROM DUAL" statement return the calculated value of an expression. "DUAL" is a dummy table in the server. The tutorial exercise below shows you some good examples:

SELECT 'Hello world!' FROM DUAL;

Hello world!

SELECT (1+2)*3/4 FROM DUAL;

2.2500

SELECT TRUE FROM DUAL;

1

SELECT TRUE AND FALSE FROM DUAL;

0

SELECT TIME(SYSDATE()) FROM DUAL;

21:30:26