用SQL语句获取常见的几种日期

用SQL语句获取常见的几种日期数值

---上周
SELECT TO_CHAR(TRUNC(SYSDATE, \'IW\') - 7, \'yyyymmdd\') FROM DUAL
SELECT TO_CHAR(TRUNC(SYSDATE, \'IW\') - 1, \'yyyymmdd\') FROM DUAL

---本周
SELECT TO_CHAR(TRUNC(SYSDATE, \'IW\') , \'yyyymmdd\') FROM DUAL
SELECT TO_CHAR(TRUNC(SYSDATE, \'IW\') + 6, \'yyyymmdd\') FROM DUAL

---上一月的第一天和最后一天
select trunc(add_months(sysdate, -1), \'mm\') first_day,
       last_day(add_months(sysdate, -1)) last_day
  from dual
---本月的最后一天
SELECT TO_CHAR(last_day(add_months(sysdate, 0)), \'yyyymmdd\') FROM DUAL

---当年 第一天
SELECT TO_CHAR(trunc(sysdate, \'yyyy\'), \'yyyymmdd\') FROM DUAL
---上年最后一天
SELECT TO_CHAR(trunc(sysdate,\'iyyy\'), \'yyyymmdd\') FROM DUAL

---当月第一天
SELECT TO_CHAR(trunc(sysdate,\'mm\'), \'yyyymmdd\') FROM DUAL
---当月数值
SELECT TO_CHAR(sysdate,\'mm\') FROM DUAL

---当周数值
SELECT TO_CHAR(sysdate,\'ww\') FROM DUAL