ROUND与TRUNC

ROUND与TRUNC
 
ROUND(n1,n2)
根据n2对n1进行四舍五入，n2缺省为0，也就是对n1取整，若n2为正数，则从n1小数点右边n2位开始四舍五入；若n2为负数，则从n1小数点左边n2位开始四舍五入。
 
SQL> select round(3456.6543),round(3456.6543,2),round(3456.6543,-2) from dual;
 
ROUND(3456.6543) ROUND(3456.6543,2) ROUND(3456.6543,-2)
---------------- ------------------ -------------------
            3457            3456.65                3500
 
TRUNC(n1,n2)
TRUNC与ROUND类似，但是TRUNC不进行四舍五入，只进行按位截取
 
SQL> select trunc(3456.6543),trunc(3456.6543,2),trunc(3456.6543,-2) from dual;
 
TRUNC(3456.6543) TRUNC(3456.6543,2) TRUNC(3456.6543,-2)
---------------- ------------------ -------------------
            3456            3456.65                3400
 
作者 “To_Be_Monster_Of_IT”