oracle常用時間查詢

--- 當前時間
SELECT sysdate FROM dual

-- 上一個小時
SELECT to_char(sysdate-1/24, 'yyyy-MM-dd HH24') FROM dual

--- 前一天
SELECT to_char(sysdate-1, 'yyyy-MM-dd') FROM dual

--- 上一個月
SELECT to_char(add_months(trunc(sysdate),-1), 'yyyy-MM') FROM dual

--- 上季度包含月份
SELECT to_char(add_months(add_months(TRUNC(sysdate, 'YYYY'), A * 3), - ROWNUM), 'YYYY-MM') LAST_Q
FROM (SELECT to_char(sysdate, 'Q')-1 A FROM DUAL)
CONNECT BY ROWNUM  <= 3
ORDER BY 1