DB2时间

SELECT DAYS(TIMESTAMP('2006-10-10 00:00:00.0')) - DAYS(TIMESTAMP('2006-4-13 00:00:00.0')) FROM DUAL;
----当前日期减去180天后的日期
SELECT current date - 180 DAYS FROM sysibm.sysdummy1;

------返回（）中日期是当年的第几天
SELECT DAYOFYEAR('2006-1-1') FROM sysibm.sysdummy1;

------返回（）中日期是当年的第几周
SELECT WEEK('2006-11-30') FROM sysibm.sysdummy1;

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select TO_CHAR_ORA(SYSDATE(),'mm') from dual;

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select TO_CHAR_ORA(SYSDATE(),'dd')  from dual;

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SELECT TO_CHAR_ORA(SYSDATE(),'YYYY-MM-DD') FROM DUAL;

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select TO_CHAR_ORA(SYSDATE(),'yyyy')  from dual;