用SQL語句獲取常見的幾種日期

用SQL語句獲取常見的幾種日期數值

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

---本週
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後一天
select trunc(add_months(sysdate, -1), 'mm') first_day,
       last_day(add_months(sysdate, -1)) last_day
  from dual
---本月的最後一天
SELECT TO_CHAR(last_day(add_months(sysdate, 0)), 'yyyymmdd') FROM DUAL

---當年 第一天
SELECT TO_CHAR(trunc(sysdate, 'yyyy'), 'yyyymmdd') FROM DUAL
---上年最後一天
SELECT TO_CHAR(trunc(sysdate,'iyyy'), 'yyyymmdd') FROM DUAL

---當月第一天
SELECT TO_CHAR(trunc(sysdate,'mm'), 'yyyymmdd') FROM DUAL
---當月數值
SELECT TO_CHAR(sysdate,'mm') FROM DUAL

---當週數值
SELECT TO_CHAR(sysdate,'ww') FROM DUAL