OracleSQL内置函数大全之二

24.LN 返回一个数字的对数值

SQL> select ln(1),ln(2),ln(2.7182818) from dual;

LN(1)     LN(2) LN(2.7182818)

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

0 .69314718     .99999999

25.LOG(n1,n2) 返回一个以n1为底n2的对数

SQL> select log(2,1),log(2,4) from dual;

LOG(2,1)  LOG(2,4)

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

0         2

26.MOD(n1,n2) 返回一个n1除以n2的余数

SQL> select mod(10,3),mod(3,3),mod(2,3) from dual;

MOD(10,3)  MOD(3,3)  MOD(2,3)

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

1         0         2

27.POWER 返回n1的n2次方根

SQL> select power(2,10),power(3,3) from dual;

POWER(2,10) POWER(3,3)

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

1024         27

28.ROUND和TRUNC

按照指定的精度进行舍入

SQL> select round(55.5),round(-55.4),trunc(55.5),trunc(-55.5) from dual;

ROUND(55.5) ROUND(-55.4) TRUNC(55.5) TRUNC(-55.5)

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

56          -55          55          -55

29.SIGN 取数字n的符号,大于0返回1,小于0返回-1,等于0返回0