生成1-10范围内的随机数 [英] Generate a random number in the range 1 - 10

问题描述

由于我在此问题中进行过测试查询，所以无法解决，我现在正在尝试其他方法。有没有办法告诉pg的 random（）函数让我只得到1到10之间的数字？

Since my approach for a test query which I worked on in this question did not work out, I'm trying something else now. Is there a way to tell pg's random() function to get me only numbers between 1 and 10?

推荐答案

如果按1到10之间的数字表示，则任何大于等于1且小于< 10，这很容易：

If by numbers between 1 and 10 you mean any float that is >= 1 and < 10, then it's easy:

select random() * 9 + 1

可以很容易地通过以下方法进行测试：

This can be easily tested with:

# select min(i), max(i) from (
    select random() * 9 + 1 as i from generate_series(1,1000000)
) q;
       min       |       max
-----------------+------------------
 1.0000083274208 | 9.99999571684748
(1 row)

如果要使用整数，则> = 1和< ; 10，那么很简单：

If you want integers, that are >= 1 and < 10, then it's simple:

select trunc(random() * 9 + 1)

再次，简单测试：

# select min(i), max(i) from (
    select trunc(random() * 9 + 1) as i from generate_series(1,1000000)
) q;
 min | max
-----+-----
   1 |   9
(1 row)

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