SQL> select sysdate from dual;
SYSDATE
-----------
2018/7/31 2
SQL> select to_char(sysdate,'yyyy-mm-dd HH24:mm:ss') from dual;
TO_CHAR(SYSDATE,'YYYY-MM-DDHH2
------------------------------
2018-07-31 22:07:35
SQL> select * next_day from dual;
select * next_day from dual
ORA-00923: 未找到要求的 FROM 关键字
SQL> select next_day(sysdate) from dual;
select next_day(sysdate) from dual
ORA-00909: 参数个数无效
SQL> select to_date("2012-04-12","yyyy-MM-dd") from dual;
select to_date("2012-04-12","yyyy-MM-dd") from dual
ORA-00904: "yyyy-MM-dd": 标识符无效
SQL> select to_date("2012-04-12","yyyy-MM-dd") from dual;
select to_date("2012-04-12","yyyy-MM-dd") from dual
ORA-00904: "yyyy-MM-dd": 标识符无效
SQL> select to_date('2012-04-12','yyyy-MM-dd') from dual;
TO_DATE('2012-04-12','YYYY-MM-
------------------------------
2012/4/12
SQL> select add_months(sysdate,3) from dual;
ADD_MONTHS(SYSDATE,3)
---------------------
2018/10/31 22:33:43
SQL> select months_between(sysdate,sysdate+3);
select months_between(sysdate,sysdate+3)
ORA-00923: 未找到要求的 FROM 关键字
SQL> select months_between(sysdate,sysdate+3) from dual;
MONTHS_BETWEEN(SYSDATE,SYSDATE
------------------------------
-0.0967741935483871
SQL> select next_day(sysdate)from dual;
select next_day(sysdate)from dual
ORA-00909: 参数个数无效
SQL> select next_day(sysdate,1) from dual;
NEXT_DAY(SYSDATE,1)
-------------------
2018/8/5 22:35:16
SQL> select to_char(sysdate,"yyyy-mm-dd hh12:MI:ss ")from dual;
select to_char(sysdate,"yyyy-mm-dd hh12:MI:ss ")from dual
ORA-00904: "yyyy-mm-dd hh12:MI:ss ": 标识符无效
SQL> select to_char(sysdate,'yyyy-mm-dd hh12:MI:ss')from dual;
TO_CHAR(SYSDATE,'YYYY-MM-DDHH1
------------------------------
2018-07-31 10:36:43
SQL> select to_char(sysdate,'yyyy-mm-dd hh:MM:ss') from dual;
2
SQL> select to_char(sysdate,'yyyy-mm-dd hh:MM:ss') from dual;
TO_CHAR(SYSDATE,'YYYY-MM-DDHH:
------------------------------
2018-07-31 10:07:14
SQL> select current_date() from dual;
select current_date() from dual
ORA-00923: 未找到要求的 FROM 关键字
SQL> select current_date from dual;
CURRENT_DATE
------------
2018/7/31 22
SQL> SELECT SESSIONTIMEZONE CURRENT_DA
2 ;
SESSIONTIMEZONE CURRENT_DA
ORA-00900: 无效 SQL 语句
SQL> SELECT SESSIONTIMEZONE CURRENT_DA
2 FROM DUAL;
CURRENT_DA
---------------------------------------------------------------------------
+08:00
SQL> SELECT DBTIMEZONE FROM DUAL;
DBTIMEZONE
----------
+00:00
SQL> SELECT EXACT(MONTH FROM YEAR )FROM DAUL;
SELECT EXACT(MONTH FROM YEAR )FROM DAUL
ORA-00907: 缺失右括号
SQL> SELECT EXACT(MONTH FROM YEAR )"THIS MONTH" FROM DUAL;
SELECT EXACT(MONTH FROM YEAR )"THIS MONTH" FROM DUAL
ORA-00907: 缺失右括号
SQL> select extract(month from sysdate) "This Month" from dual;
This Month
----------
7
SQL> SELECT LOCALTIMESTAMP FROM DUAL;
LOCALTIMESTAMP
--------------------------------------------------------------------------------
31-7月 -18 10.43.25.968000 下午
SQL> SELECT TO_CHAR(SYSDATE,'DY')FROM DUAL;
TO_CHAR(SYSDATE,'DY')
---------------------
星期二
SQL> SELECT TO_DATE(SYSDATE,'HH24') FROM DUAL;
SELECT TO_DATE(SYSDATE,'HH24') FROM DUAL
ORA-01850: 小时值必须介于 0 和 23 之间
SQL> SELECT TO_DATE(SYSDATE,'HH24') FROM DUAL;
SELECT TO_DATE(SYSDATE,'HH24') FROM DUAL
ORA-01850: 小时值必须介于 0 和 23 之间
SQL> SELECT TO_CHAR(SYSDATE,'MI')FROM DUAL;
TO_CHAR(SYSDATE,'MI')
---------------------
45
SQL> SELECT TO_CHAR(ADD_MONTHS(LAST_DAY(SYSDATE),-1),'yyyy-MM-dd HH:mm:ss')
2 from dual;
TO_CHAR(ADD_MONTHS(LAST_DAY(SY
------------------------------
2018-06-30 10:06
SQL> select add_months(sysdate,-1) from dual;
ADD_MONTHS(SYSDATE,-1)
----------------------
2018/6/30 22:50:24
SQL> select last_week(sysdate) from dual;
select last_week(sysdate) from dual
ORA-00904: "LAST_WEEK": 标识符无效
SQL> select last_weeks(sysdate) from dual;
select last_weeks(sysdate) from dual
ORA-00904: "LAST_WEEKS": 标识符无效
SQL> select last_weekday(sysdate) from dual;
select last_weekday(sysdate) from dual
ORA-00904: "LAST_WEEKDAY": 标识符无效
SQL> selct add_months(last_day(sysdate)+1,-2) from dual ;
selct add_months(last_day(sysdate)+1,-2) from dual
ORA-00900: 无效 SQL 语句
SQL> select add_months(last_day(sysdate)+1,-2) from dual ;
ADD_MONTHS(LAST_DAY(SYSDATE)+1
------------------------------
2018/6/1 22:56:22
SQL> select to char('sysdate','q') from dual group by to_char(sysdate,'q');
select to char('sysdate','q') from dual group by to_char(sysdate,'q')
ORA-00936: 缺失表达式
SQL> select to_char('sysdate','q') from dual group by to_char(sysdate,'q');
select to_char('sysdate','q') from dual group by to_char(sysdate,'q')
ORA-01722: 无效数字
SQL> show error;
No errors
SQL> select to_char(sysdate,'q') from dual group by to_char(sysdate,'q');
TO_CHAR(SYSDATE,'Q')
--------------------
3
SQL>
SQL> select to_char(t.d,'YY-MM-DD') from (
2 select trunc(sysdate, 'MM')+rownum-1 as d
3 from dba_objects
4 where rownum < 32) t
5 where to_char(t.d, 'MM') = to_char(sysdate, 'MM') --找出当前月份的周五的日期
SQL> and trim(to_char(t.d, 'Day')) = '星期五'
2 /
and trim(to_char(t.d, 'Day')) = '星期五'
ORA-00900: 无效 SQL 语句
SQL>
SQL> select to_char(t.d,'YY-MM-DD') from (
2 select trunc(sysdate, 'MM')+rownum-1 as d
3 from dba_objects
4 where rownum < 32) t
5 where to_char(t.d, 'MM') = to_char(sysdate, 'MM') --找出当前月份的周五的日期
6 and trim(to_char(t.d, 'Day')) = '星期五' ;
select to_char(t.d,'YY-MM-DD') from (
select trunc(sysdate, 'MM')+rownum-1 as d
from dba_objects
where rownum < 32) t
where to_char(t.d, 'MM') = to_char(sysdate, 'MM') --找出当前月份的周五的日期
and trim(to_char(t.d, 'Day')) = '星期五'
ORA-00942: 表或视图不存在
SQL> conn sys/sys as sysdba;
Connected to Oracle Database 10g Enterprise Edition Release 10.2.0.3.0
Connected as SYS
SQL>
SQL> select to_char(t.d,'YY-MM-DD') from (
2 select trunc(sysdate, 'MM')+rownum-1 as d
3 from dba_objects
4 where rownum < 32) t
5 where to_char(t.d, 'MM') = to_char(sysdate, 'MM') --找出当前月份的周五的日期
6 and trim(to_char(t.d, 'Day')) = '星期五' ;
TO_CHAR(T.D,'YY-MM-DD')
-----------------------
18-07-06
18-07-13
18-07-20
18-07-27
SQL> oracle 常用的日期函数
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