Oracle计算时间函数(numtodsinterval、numtoyminterval)

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numtodsinterval(<x>,<c>) ,x是一个数字,c是一个字符串,

表明x的单位,这个函数把x转为interval day to second数据类型
常用的单位有 ('day','hour','minute','second')
example
SQL> select sysdate,sysdate+numtodsinterval(3,'hour') as res from dual;
SYSDATE             RES
------------------- -------------------
2007-09-05 01:45:34 2007-09-05 04:45:34
numtoyminterval 与numtodsinterval函数类似,将x转为interval year to month数据类型
常用的单位有'year','month'
example
SQL> select sysdate,sysdate+numtoyminterval(3,'year') as res from dual;
SYSDATE             RES
------------------- -------------------
2007-09-05 01:54:53 2010-09-05 01:54:53