1.日期時(shí)間間隔操作

當(dāng)前時(shí)間減去7分鐘的時(shí)間

select sysdate,sysdate - interval '7' MINUTE from dual

當(dāng)前時(shí)間減去7小時(shí)的時(shí)間

select sysdate - interval '7' hour from dual

當(dāng)前時(shí)間減去7天的時(shí)間

select sysdate - interval '7' day from dual

當(dāng)前時(shí)間減去7月的時(shí)間

select sysdate,sysdate - interval '7' month from dual

當(dāng)前時(shí)間減去7年的時(shí)間

select sysdate,sysdate - interval '7' year from dual

時(shí)間間隔乘以一個(gè)數(shù)字

select sysdate,sysdate - 8 *interval '2' hour from dual

2.日期到字符操作

select sysdate,to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual

select sysdate,to_char(sysdate,'yyyy-mm-dd hh:mi:ss') from dual

select sysdate,to_char(sysdate,'yyyy-ddd hh:mi:ss') from dual

select sysdate,to_char(sysdate,'yyyy-mm iw-d hh:mi:ss') from dual

參考o(jì)racle的相關(guān)關(guān)文檔(ORACLE901DOC/SERVER.901/A90125/SQL_ELEMENTS4.HTM#48515)

3. 字符到日期操作

select to_date('2003-10-17 21:15:37','yyyy-mm-dd hh24:mi:ss') from dual

具體用法和上面的to_char差不多。

4. trunk/ ROUND函數(shù)的使用

select trunc(sysdate ,'YEAR') from dual

select trunc(sysdate ) from dual

select to_char(trunc(sysdate ,'YYYY'),'YYYY') from dual

5.oracle有毫秒級的數(shù)據(jù)類型

--返回當(dāng)前時(shí)間 年月日小時(shí)分秒毫秒

select to_char(current_timestamp(5),'DD-MON-YYYY HH24:MI:SSxFF') from dual;

--返回當(dāng)前 時(shí)間的秒毫秒，可以指定秒后面的精度(最大=9)

select to_char(current_timestamp(9),'MI:SSxFF') from dual;

6.計(jì)算程序運(yùn)行的時(shí)間(ms)

declare

type rc is ref cursor;

l_rc rc;

l_dummy all_objects.object_name%type;

l_start number default dbms_utility.get_time;

begin

for I in 1 .. 1000

loop

open l_rc for

'select object_name from all_objects '||

'where object_id = ' || i;

fetch l_rc into l_dummy;