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Accepted
humberto herrara
Asked: 2020-07-25 08:41:13 +0800 CST

结果因相同的查询而异

  • 772

嗨，我的一个查询陷入了奇怪的问题。

公式：(28800/3600-(28382.6/3600-(1920/3600+1860/3600))) =

所以，输入方程：

= (28800/3600-(28382.6/3600-(1920/3600+1860/3600)))

= (28800/3600-(28382.6/3600-(0.53333333333333+1860/3600)))

= (28800/3600-(28382.6/3600-(0.53333333333333+0.51666666666667)))

= (28800/3600-(28382.6/3600-(1.05)))

= (28800/3600-(28382.6/3600-1.05))

= (28800/3600-(7.8840555555556-1.05))

= (28800/3600-(6.8340555555556))

= (28800/3600-6.8340555555556)

= (8-6.8340555555556)

= (1.1659444444444)

= 1.1659444444444

但是我从查询中得到 0 作为输出，它应该打印 1

select (to_char (NULLIF(GREATEST(coalesce(28800/3600,0) - (coalesce(28382.6/3600,0) - 
(coalesce(1920/3600,0) + (coalesce(1860/3600,0)))),0),0),'FM99,999,999,999'))::character varying as mydatas

现在，相同的公式和具有不同值的相同查询可以正常工作。请检查以下。

(28800/3600-(13552.24/3600-(900/3600+0/3600)))

输入方程：

= (28800/3600-(13552.24/3600-(900/3600+0/3600)))

= (28800/3600-(13552.24/3600-(0.25+0/3600)))

= (28800/3600-(13552.24/3600-(0.25+0)))

= (28800/3600-(13552.24/3600-(0.25)))

= (28800/3600-(13552.24/3600-0.25))

= (28800/3600-(3.7645111111111-0.25))

= (28800/3600-(3.5145111111111))

= (28800/3600-3.5145111111111)

= (8-3.5145111111111)

= (4.4854888888889)

= 4.4854888888889

所以我的查询也给出了 4 作为输出

select (to_char (NULLIF(GREATEST(coalesce(28800/3600,0) - (coalesce(13552.24/3600,0) - 
(coalesce(900/3600,0) + (coalesce(0/3600,0)))),0),0),'FM99,999,999'))::character varying as mydatas
postgresql query-performance

1 个回答

  1. Best Answer

    表达方式：

    select ((NULLIF(GREATEST(coalesce(28800/3600,0) - (coalesce(28382.6/3600,0) - 
(coalesce(1920/3600,0) + (coalesce(1860/3600,0)))),0),0)))::character varying as mydatas

    评估为 0.11594...

    你在这一步弄错了：

    = select (28800/3600-(28382.6/3600-(1920/3600+1860/3600)));

= select (28800/3600-(28382.6/3600-(0.53333333333333+0.51666666666667))); -- False

    因为 1920/3600 = 0，所以 1860/3600 由于整数除法。您可以通过确保其中一个操作数不是整数类型来修复您的表达式，例如：

    = select (28800.0/3600-(28382.6/3600-(1920.0/3600+1860.0/3600)));

    小提琴

    • 3

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