determining percentages with php - php

Question

I am trying to determine the percentage of number of student passing a test either on 1st attempt or 2nd attempt. I believe I have the code correct but when I echo the results I get no output.
<?php
$NREMT1 = "SELECT nremtcognitive FROM course_students WHERE nremtcognitive = '1' ";
$NREMT2 = "SELECT nremtcognitive FROM course_students WHERE nremtcognitive >= '2' ";
$completed = "SELECT studentstatus FROM course_students WHERE studentstatus >='4'";
$getNREMT1 = mysql_query($NREMT1);
$fetchNREMT1= mysql_num_rows($getNREMT1);
$getNREMT2 = mysql_query($NREMT2);
$fetchNREMT2= mysql_num_rows($getNREMT2);
$getcompleted = mysql_query($completed);
$fetchcompleted= mysql_num_rows($getcompleted);
function percent($fetchNREMT1, $fetchNREMT2, $fetchcompleted) {
$NREMT1count= $fetchNREMT1/$fetchcompleted;
$NREMT1percent= $NREMT1count * 100;
$NREMT1result = number_format($NREMT1percent,0);
$NREMT2count= $fetchNREMT2/$fetchcompleted;
$NREMT2percent= $NREMT2count * 100;
$NREMT2result = number_format($NREMT2percent,0);
}
echo $NREMT1result;
echo $NREMT2result;
?>

Answer 1

You are not calling your function percent anywhere.
You should call it and make it return something or otherwise, just can avoid creating it and put the same code in the same place:
$NREMT1count= $fetchNREMT1/$fetchcompleted;
$NREMT1percent= $NREMT1count * 100;
$NREMT1result = number_format($NREMT1percent,0);
$NREMT2count= $fetchNREMT2/$fetchcompleted;
$NREMT2percent= $NREMT2count * 100;
$NREMT2result = number_format($NREMT2percent,0);
echo $NREMT1result;
echo $NREMT2result;
It seems you don't have it very clear the concept of function. You can take a look at the documentation.

Answer 2

Your problem is that the variables declared inside percent() are never initialized because the function is never called. Try this:
<?php
$NREMT1 = "SELECT nremtcognitive FROM course_students WHERE nremtcognitive = '1' ";
$NREMT2 = "SELECT nremtcognitive FROM course_students WHERE nremtcognitive >= '2' ";
$completed = "SELECT studentstatus FROM course_students WHERE studentstatus >='4'";
$getNREMT1 = mysql_query($NREMT1);
$fetchNREMT1= mysql_num_rows($getNREMT1);
$getNREMT2 = mysql_query($NREMT2);
$fetchNREMT2= mysql_num_rows($getNREMT2);
$getcompleted = mysql_query($completed);
$fetchcompleted= mysql_num_rows($getcompleted);
percent($fetchNREMT1, $fetchNREMT2, $fetchcompleted);
function percent($fetchNREMT1, $fetchNREMT2, $fetchcompleted) {
$NREMT1count= $fetchNREMT1/$fetchcompleted;
$NREMT1percent= $NREMT1count * 100;
$NREMT1result = number_format($NREMT1percent,0);
$NREMT2count= $fetchNREMT2/$fetchcompleted;
$NREMT2percent= $NREMT2count * 100;
$NREMT2result = number_format($NREMT2percent,0);
echo $NREMT1result;
echo $NREMT2result;
}
?>
It is also worth noting that the mysql_* family of functions are now deprecated, and you should really consider using MySQLi or PDO.

Answer 3

Just change your query. Untested, but this should get you started:
SELECT
SUM(IF(CONVERT(nremtcognitive, UNSIGNED INTEGER) >= 2)) / COUNT(*)
FROM course_students;