SQL内置函数的使用方法及结果(6)

33.TAN 返回数字的正切值

SQL> select tan(20),tan(10) from dual;

TAN(20) TAN(10)

--------- ---------

2.2371609 .64836083

34.TANH

返回数字n的双曲正切值

SQL> select tanh(20),tan(20) from dual;

TANH(20) TAN(20)

--------- ---------

1 2.2371609

35.TRUNC

按照指定的精度截取一个数

SQL> select trunc(124.1666,-2) trunc1,trunc(124.16666,2) from dual;

TRUNC1 TRUNC(124.16666,2)

--------- ------------------

100 124.16

36.ADD_MONTHS

增加或减去月份

SQL> select to_char(add_months(to_date("199912","yyyymm"),2),"yyyymm") from dual;

TO_CHA

------

200002

SQL> select to_char(add_months(to_date("199912","yyyymm"),-2),"yyyymm") from dual;

TO_CHA

------

199910

37.LAST_DAY

返回日期的最后一天

SQL> select to_char(sysdate,"yyyy.mm.dd"),to_char((sysdate)+1,"yyyy.mm.dd") from dual;

TO_CHAR(SY TO_CHAR((S

---------- ----------

2004.05.09 2004.05.10

SQL> select last_day(sysdate) from dual;

LAST_DAY(S

----------

31-5月 -04