which two statements are true?
A. SELECT TO_DATE('2019-DEC-25 15:30','YYYY-MM-DD HH24:MI','NLS_DATE_LANGUAGE=AMERICAN') FROM DUAL;
B. SELECT TO_CHAR('2019-DEC-25 03:30','YYYY-MM-DD HH24:MI') FROM DUAL;
C. SELECT TO_CHAR(TO_DATE('2019-DEC-25 03:30','YYYY-MON-DD HH12:MI')) FROM DUAL;
D. SELECT TO_CHAR('2019-DEC-25 15:30','YYYY-MM-DD HH24:MI','NLS_DATE_LANGUAGE=AMERICAN') FROM DUAL;
E. SELECT TO_DATE(TO_CHAR('2019-DEC-25 03:30','YYYY-MON-DD HH12:MI')) FROM DUAL;
Answer: AC
Explanation:
TO_CHAR 函数括号内第一个值必须为日期型处理字段，不能为字符；为字符型日期格式的全部语法错误，直接排除 BDE
执行结果如下：
A. 2019-12-25 15:30:00
B. ORA-01722: invalid number
C. 2019-12-25 03:30:00
D. ORA-01722: invalid number
E. ORA-01722: invalid number
提示：答案为个人理解和解答，难免有错，也欢迎大家及时指正。