Question

Which of the following is illegal?

(a) SELECT SYSDATE – SYSDATE FROM DUAL;

(b) SELECT SYSDATE – (SYSDATE – 2) FROM DUAL;

(c) SELECT SYSDATE – (SYSDATE + 2) FROM DUAL;

(d) None of the Mentioned

The question was asked in my homework.

The above asked question is from Structured Query Language in section SQL Basics of Oracle

Answer 1

Right answer is (d) None of the Mentioned

The best explanation: SELECT SYSDATE – SYSDATE FROM DUAL; outputs 0 SELECT SYSDATE – (SYSDATE – 2) FROM DUAL; outputs 2

SELECT SYSDATE – (SYSDATE + 2) FROM DUAL; outputs -2.