Oracle中的to_date参数含义

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

select sysdate - interval ’7’ hour from dual

 select sysdate - interval ’7’ day from dual

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

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

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

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

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

select trunc(sysdate ,’YEAR’) from dual 

select trunc(sysdate ) from dual 

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

--返回当前时间 年月日小时分秒毫秒 

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

--返回当前 时间的秒毫秒，可以指定秒后面的精度(最大=9) 

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

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;