oracle日期相关函数

1、查询上月的所有日期： SELECT TO_CHAR (TRUNC (TRUNC (SYSDATE, 'MM') - 1, 'month') + LEVEL - 1, 'yyyy-MM-dd') AS month_day FROM DUAL CONNECT BY LEVEL <= TO_CHAR (LAST_DAY (TRUNC (SYSDATE, 'MM') - 1), 'dd'); 2、查询当月的所有日期： SELECT TO_CHAR (TRUNC (SYSDATE, 'month') + LEVEL - 1, 'yyyy-MM-dd') AS month_day FROM DUAL CONNECT BY LEVEL <= TO_CHAR (LAST_DAY (TRUNC (SYSDATE, 'MM') - 1), 'dd'); 3、查询上月月份： SELECT TO_CHAR(ADD_MONTHS(SYSDATE,-1),'YYYY-MM') FROM DUAL; 4、查询当月天数： SELECT TO_CHAR (LAST_DAY (TRUNC (SYSDATE, 'mm')), 'DD') mounth_count FROM DUAL; 5、查询当月第一天： SELECT TRUNC (SYSDATE, 'month') FROM DUAL; 6、查询当月最后一天： SELECT TO_CHAR (LAST_DAY (SYSDATE), 'YYYY-MM-DD') FROM DUAL; 7、计算两个日期之间天数： SELECT TO_DATE ('2013-08-05', 'yyyy-MM-dd') - TO_DATE ('2013-08-01', 'yyyy-MM-dd') + 1 AS count_day FROM DUAL; 8、查询两个日期之间的所有日期： SELECT ROWNUM, TO_DATE ('2013-01-02', 'yyyy-MM-dd') + ROWNUM - 1 AS allday FROM DUAL CONNECT BY ROWNUM < TO_DATE ('2013-01-07', 'yyyy-MM-dd') - TO_DATE ('2013-01-02', 'yyyy-MM-dd') + 2;