SUM在while循环-PHP

Question

I have a loop which extracts 2 numbers from a table and then calculates the total.

I want to find the final total (sum of all totals).

Is there a way to not use the DB to calculate the SUM but do it within the loop.

while($row = $result->fetch_assoc()) {

   $total= $row["num1"] + $row["num2"];

}

How do I do this?

This is wrong:

while($row = $result->fetch_assoc()) {

   $total= $row["num1"] + $row["num2"];

   $total = $total + $total;

}

Answer 1

$total=0;
while($row = $result->fetch_assoc()) {

   $sum= $row["num1"] + $row["num2"];

   $total = $total + $sum;

}

Answer 2

Simply initialize your $total outside the while Loop to zero and then add to it like so:

<?php

    $total     = 0;

    while($row = $result->fetch_assoc()) {
       $total += ($row["num1"] + $row["num2"]);

    }

Answer 3

You can simply add to the overall total with each iteration of the loop:

<?php 
$total = 0;
while($row = $result->fetch_assoc()) {
   $total += $row['num1'] + $row['num2'];
}

Actually in php you are not even required to initialize the $total variable as shown, but it is considered good practice, since it raises the readability of the code.

Doing this on the level of a scripting language obviously is much less efficient than using the db engine itself to calculate the sum. But I assume this is not a real works task, but some seminar homework or similar...

Answer 4

$total = 0;

while($row = $result->fetch_assoc()) {
   $total += $row["num1"] + $row["num2"];
}