1、求某个月有多少天
SQL> select sysdate,to_number(to_char(last_day(sysdate),'DD')) from dual;
SYSDATE TO_NUMBER(TO_CHAR(LAST_DAY(SYSDATE),'DD'))
--------- ------------------------------------------
28-JUN-19 30
2、计算一个月还剩多少天
SQL> select sysdate,last_day(sysdate)-sysdate from dual;
SYSDATE LAST_DAY(SYSDATE)-SYSDATE
--------- -------------------------
28-JUN-19 2
3、今天是星期几
SQL> select to_char(sysdate,'DAY') from dual;
TO_CHAR(SYSDATE,'DAY')
------------------------------------
FRIDAY
4、今天是几号
SQL> select extract(DAY from sysdate) from dual;
EXTRACT(DAYFROMSYSDATE)
-----------------------
28
5、今天是一年的第几天
SQL> select to_char(sysdate,'DDD') from dual;
TO_
---
179