ORACLE 常用表达式
取日期：
/*****************************************oracle 日期相关操作***************************************/--求当前年第一天select trunc(sysdate,'yyyy') from dual;--求当前月第一天select trunc(sysdate,'mm') from dual;--求当前周第一天select trunc(sysdate,'d') from dual;--求月天数select to_char(last_day(sysdate),'dd') from dual; --求年天数select trunc(add_months(sysdate,12),'yyyy')-trunc(sysdate,'yyyy') nts from dual;--求当前月所在季度select to_char(sysdate,'q') from dual;--求当天是星期几select to_char(sysdate,'dy') rq from dual;--求当前周是当月第几周select to_char(sysdate,'w') rq from dual;--求当前周是今年第几周select to_char(sysdate,'ww') rq from dual;--求当前季度第一天select trunc(sysdate,'q') from dual;--列出当月所有日期select trunc(sysdate,'mm') +rownum-1 from dual connect by rownum<=to_char(last_day(sysdate),'dd');--列出当年所有日期select trunc(sysdate,'yyyy')+rownum-1 from dual connect by rownum<=365;
