SQL 中四舍五入到 n 个有效数字 [英] Round to n Significant Figures in SQL

问题描述

我希望能够在 SQL 中将数字四舍五入为 n 个有效数字.所以:

I would like to be able to round a number to n significant figures in SQL. So:

123.456 rounded to 2sf would give 120
0.00123 rounded to 2sf would give 0.0012

我知道 ROUND() 函数，它四舍五入到 n 个小数位而不是有效数字.

I am aware of the ROUND() function, which rounds to n decimal places rather than significant figures.

推荐答案

select round(@number,@sf-1- floor(log10(abs(@number)))) 应该做的把戏！

在您的两个示例上成功测试.

Successfully tested on your two examples.

在@number=0 上调用此函数将不起作用.在使用此代码之前，您应该为此添加一个测试.

Edit : Calling this function on @number=0 won't work. You should add a test for this before using this code.

create function sfround(@number float, @sf int) returns float as
begin
    declare @r float
    select @r = case when @number = 0 then 0 else round(@number ,@sf -1-floor(log10(abs(@number )))) end
    return (@r)
end

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