Oracle關于時間/日期的操作
1.日期時間間隔操作
當前時間減去7分鐘的時間
select? sysdate,sysdate - interval '7' MINUTE? from dual
當前時間減去7小時的時間
select? sysdate - interval '7' hour? from dual
當前時間減去7天的時間
select? sysdate - interval '7' day? from dual
當前時間減去7月的時間
select? sysdate,sysdate - interval '7' month from dual
當前時間減去7年的時間
select? sysdate,sysdate - interval '7' year?? from dual
時間間隔乘以一個數字
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oracle的相關關文檔(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有毫秒級的數據類型
--返回當前時間 年月日小時分秒毫秒
select to_char(current_timestamp(5),'DD-MON-YYYY HH24:MI:SSxFF') from dual;
--返回當前 時間的秒毫秒，可以指定秒后面的精度(最大=9)
select to_char(current_timestamp(9),'MI:SSxFF') from dual;
6.計算程序運行的時間(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;
??????? close l_rc;
??? end loop;
??? dbms_output.put_line
??? ( round( (dbms_utility.get_time-l_start)/100, 2 ) ||
????? ' seconds...' );
end;