oracle单行函数之日期函数

 1 SQL> select sysdate ,sysdate+2 from dual;
 2  
 3 SYSDATE     SYSDATE+2
 4 ----------- -----------
 5 2014-12-23  2014-12-25
 6  
 7 SQL> select hiredate,sysdate-hiredate from emp;
 8  
 9 HIREDATE    SYSDATE-HIREDATE
10 ----------- ----------------
11 1980-12-17  12424.8094328704
12 1981-2-20   12359.8094328704
13 1981-2-22   12357.8094328704
14 1981-4-2    12318.8094328704
15 1981-9-28   12139.8094328704
16 1981-5-1    12289.8094328704
17 1981-6-9    12250.8094328704
18 1981-11-17  12089.8094328704
19 1981-9-8    12159.8094328704
20 1981-12-3   12073.8094328704
21 1981-12-3   12073.8094328704
22 1982-1-23   12022.8094328704
23  
24 13 rows selected
25  

 1 SQL> select sysdate,add_months(sysdate,2) from dual;
 2  
 3 SYSDATE     ADD_MONTHS(SYSDATE,2)
 4 ----------- ---------------------
 5 2014-12-23  2015-2-23 下午 07:30:25
 6 
 7 SQL> select sysdate,add_months(sysdate,2) from dual;
 8  
 9 SYSDATE     ADD_MONTHS(SYSDATE,2)
10 ----------- ---------------------
11 2014-12-23  2015-2-23 下午 07:30:25
12  
13 SQL> select sysdate,next_day(sysdate,‘星期一‘) from dual;
14  
15 SYSDATE     NEXT_DAY(SYSDATE,‘星期一‘)
16 ----------- --------------------------
17 2014-12-23  2014-12-29 下午 07:31:34
18  
19 SQL> select sysdate, last_day(sysdate) from dual;
20  
21 SYSDATE     LAST_DAY(SYSDATE)
22 ----------- -----------------
23 2014-12-23  2014-12-31 下午 07:
24  
25  
26 SQL> select round(sysdate,‘month‘),trunc(sysdate,‘month‘) from dual;
27  
28 ROUND(SYSDATE,‘MONTH‘) TRUNC(SYSDATE,‘MONTH‘)
29 ---------------------- ----------------------
30 2015-1-1               2014-12-1