ORACLE³£Óù¦ÄÜ

-- ɾ³ýÖظ´¼Ç¼
DELETE from mytable t1 WHERE ROWID > (SELECT MIN (ROWID) from mytable t2 WHERE t1. key = t2.key);
-- µ±Ç°ÈÕÆÚ
SELECT TO_CHAR(SYSDATE, 'yyyy-MM-dd') from DUAL;
-- ÉÏÔµ±Ç°ÈÕÆÚ
SELECT TO_CHAR(ADD_MONTHS(SYSDATE,
-1), 'yyyy-MM-dd') from DUAL;
-- ÏÂÔµ±Ç°ÈÕÆÚ
SELECT
TO_CHAR(ADD_MONTHS(SYSDATE, 1), 'yyyy-MM-dd') from DUAL;
--
ÉÏÔÂÊ×Ìì
SELECT TO_CHAR(ADD_MONTHS(LAST_DAY(SYSDATE) + 1,
-2),'yyyy-MM-dd') from DUAL;
-- ÉÏÔÂÔÂÄ©
SELECT
TO_CHAR(LAST_DAY(ADD_MONTHS(LAST_DAY(SYSDATE) + 1, -2)),'yyyy-MM-dd') from DUAL;
-- µ±ÔÂÊ×Ìì
SELECT
TO_CHAR(ADD_MONTHS(LAST_DAY(SYSDATE) + 1, -1), 'yyyy-MM-dd') from DUAL;
-- µ±ÔÂÔÂÄ©
SELECT
TO_CHAR(LAST_DAY(ADD_MONTHS(LAST_DAY(SYSDATE) + 1, -1)),'yyyy-MM-dd') from DUAL;
-- ÏÂÔÂÊ×Ìì
SELECT
TO_CHAR(ADD_MONTHS(LAST_DAY(SYSDATE) + 1, 0), 'yyyy-MM-dd') from DUAL;
-- ÏÂÔÂÔÂÄ©
SELECT
TO_CHAR(LAST_DAY(ADD_MONTHS(LAST_DAY(SYSDATE) + 1, 0)), 'yyyy-MM-dd') from DUAL;
-- ½ñÄêÊ×Ìì
SELECT TO_CHAR(TRUNC(SYSDATE,'Y'), 'yyyy-MM-dd') from DUAL;