小编pre*_*se6的帖子

如何从以下两个查询中获得不同的结果？a,b,c是浮点数,我认为它们会返回相同的结果,但它们稍微偏离.

SELECT (a-b)+(c) 
FROM
    (
            select  sum([Actual Freight Per Line Amt]) a, 
                    sum([fedex charge per line amt]) b, 
                    sum([inbound freight cost]) c 
             from stg.invoices where year([gl date]) = '2016'
    ) foo

结果:-5822899.31314175

&

SELECT SUM((a-b)+(c))
FROM
    (
            select  [Actual Freight Per Line Amt] a, 
                    [fedex charge per line amt] b, 
                    [inbound freight cost] c 
             from stg.invoices where year([gl date]) = '2016'
    ) foo

结果:-5796251.59304654