Oracle技术：Oracle30秒后的系统时间

会计考友

select sysdate,sysdate+1/24/60/60*30 from dual; 　　select sysdate,sysdate+30/(24*60*60) from dual;
( Q9 j5 H: ?9 U4 v% R. i2 D( T7 j　　select sysdate,sysdate+(0.5/24/60) from dual;
　　select sysdate,sysdate+(interval '30' second) from dual;