DBMS_RANDOM

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开发过程中经常会有产生随机数的需求，而oracle本身自带的有这样的功能，下面介绍一下拥有此功能的包DBMS_RANDOM，主要以官方文档来说明：

The DBMS_RANDOM package provides a built-in random number generator.

该包里包含了几个子程序，这里仅仅介绍两个：

RANDOM function

This procedure is deprecated. Although currently supported, it should not be used. It generates and returns a random number.

Syntax

DBMS_RANDOM.RANDOM   RETURN binary_integer;

Return value

A random BINARY_INTEGER value greater than or equal to -power(2,31) and less than power(2,31)

VALUE function

One version returns a random number, greater than or equal to 0 and less than 1, with 38 digits to the right of the decimal (38-digit precision). The other version returns a random Oracle Database NUMBER value x, where x is greater than or equal to the specified low value and less than the specified high value.

Syntax

DBMS_RANDOM.VALUE  RETURN NUMBER;DBMS_RANDOM.VALUE(  low  IN  NUMBER,  high IN  NUMBER)RETURN NUMBER;

Parameters

ParameterDescription

low

Lower limit of the range in which to generate a random number

high

Upper limit of the range in which to generate a random number

Return value

A NUMBER value that is the generated random number

举例：round(dbms_random.value(0,18),0) 就可以返回大于等于0且小于18的整数；