function

result

ROUND

Rounds value to a specified decimal

四舍五入

TRUNC

Truncates value to a specified decimal

截断一个值到一定的小数位，不管大于5小于5

MOD

Returns remainder of division

返回一个除数的余数

function

result

ROUND(45.926，2)

45.93

TRUNC(45.926，2)

45.92

MOD(1600，300)

100

function

purpose

ROUND(column | expression,n)

Rounds (四舍五入)the column, expression, or value to n decimal places（小数位） or, if n is omitted（省略）, no decimal places (if n degative, numbers to the left of decimal point are rounded.)

如果n是负数，小数点左边四舍五入

SQL> SELECT ROUND(45.923,2),ROUND(45.923,0),ROUND(45.923,-1) FROM DUAL;

ROUND(45.923,2) ROUND(45.923,0) ROUND(45.923,-1)

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

45.92              46               50

TRUNC(column | expression,n)

Truncates（截断） the column, expression, or value to n decimal places or, if n is omitted, n defaults to zero.

Like the ROUND function, the TRUC function can be used with date functions.

TRUNC函数也可以用作日期函数.

MOD(m,n)

Returns the remainder（余数） of m divided by n

Note : The MOD function is often used to determine whether a value is odd or even.

The MOD function is also the ORACLE hash function.

MOD函数经常被用于判断一个值是奇数还是偶数.