Results are varying with same query

All we need is an easy explanation of the problem, so here it is.

Hi I stuck in strange issue with one of my query.

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

So, Input Equation:

= (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

But I am getting 0 as output from my query, it supposed to print 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

Now, same formula and same query with different values working fine. please check following.

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

Input Equation:

= (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

so my query also gives 4 as output

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

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

The expression:

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

evaluates to 0.11594…

You are getting it wrong at this step:

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

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

Because 1920/3600 = 0 and so is 1860/3600 due to integer division. You can fix your expression by making sure that one of the operands is not an integer type, example:

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

Fiddle

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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