PHP calculation returns NAN

Question

I'm trying to perform some calculation on Data retrieved from database , but evertime I run this code I get NAN as output.

function calculateNPS()
    { 
        $queryTotal = "SELECT count(*) as total FROM message";
        $resullTotal = mysqli_query($link ,$queryTotal);

        $queryYes= "SELECT count(visit) as  yes FROM message WHERE visit='Yes'";
        $resultYes = mysqli_query($link ,$queryYes);

         $queryNo = "SELECT *count(visit) as no FROM message WHERE visit='No'";
        $resultNo = mysqli_query($link ,$queryNo);

        $yescount = mysqli_fetch_assoc($resultTotal);
        $nocount=mysqli_fetch_assoc($resultNo);
        $totalcount=mysqli_fetch_assoc($resultYes);

        $nps = ((float)($yescount['yes'])/(float)($totalcount['total'])*100)-((float)($nocount['no'])/(float)($totalcount['total'])*100);
        echo $nps;

}

SELECT *count(visit) is invalid. You'll want to echo/log the results for each to make sure they contain what you think. — aynber
– aynber, Commented Jun 2, 2020 at 19:13
@aynber corrected that a while ago, but still no change in output. — Usman
– Usman, Commented Jun 2, 2020 at 19:16
NaN sounds like it's coming from Javascript, not PHP. As I mentioned, you'll need to double-check the values of each variable by logging them or using echo/var_dump to see what they contain so you can pinpoint the issue. — aynber
– aynber, Commented Jun 2, 2020 at 19:22
@aynber PHP can display NAN when necessary. it even has a NAN keyword. — Salman Arshad
– Salman Arshad, Commented Jun 2, 2020 at 19:38

Stefan Bräu · Accepted Answer · 2020-06-02 19:24:03Z

1

I hope thats just a test-script, because there are a lot of issues you could fall into ;-)

but your problem: i guess its just a typing-mistake. you name the result-var "resullTotal", below you are requesting another var called "resultTotal" ;-)

answered Jun 2, 2020 at 19:24

Stefan Bräu

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lbrandao · Accepted Answer · 2020-06-02 20:44:23Z

0

Some numeric operations can result in a value represented by the constant NAN. This result represents an undefined or unrepresentable value in floating-point calculations. So it seems you have some problems with the values in the $nps calculation.

I would suggest that you try outputting/inspecting all the params, like $yescount or $yescount['yes'] to make sure you have valid data to start with. Then break your expression into shorter operations until you find the issue.

For instance, mysqli_fetch_assoc returns an associative array that corresponds to the fetched row or NULL if there are no more rows.

Also, in your queries you use $link but I can't see where it's coming from.

answered Jun 2, 2020 at 20:44

lbrandao

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