How to calculate kills/deaths ratio in a computer game? - php

Question

I need my computer game to take all kills and deaths from a user's total and then make it so the kills are divided by the deaths, then that total is put at the end. This ratio is known as their kill-death ratio, or "KDR".
<?php
// Create connection
$con=mysqli_connect("ipaddress","user","password","minecraft");
// Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$result = mysqli_query($con,"SELECT *, `kills`/`deaths` as `KDR` FROM war_kills ``ORDER BY kills DESC");
echo "<table border='1'>
<tr>
<th>Player</th>
<th>Kills</th>
<th>Deaths</th>
<th>KDR</th>
</tr>";
while($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['player'] . "</td>";
echo "<td>" . $row['kills'] . "</td>";
echo "<td>" . $row['deaths'] . "</td>";
echo "<td>" . $row['KDR'] . "</td>";
echo "</tr>";
}
echo "</table>";
?>
We have this up so far: http://gexgaming.com/warstats/index.php

Answer 1

Change the query from
SELECT player, kills, deaths, KDR FROM war_kills ORDER BY kills DESC`
to
SELECT player, kills, deaths, kills / deaths as KDR FROM war_kills ORDER BY kills DESC`

Answer 2

Either modify the SQL query as suggested or do it within the PHP loop:
while($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['player'] . "</td>";
echo "<td>" . $row['kills'] . "</td>";
echo "<td>" . $row['deaths'] . "</td>";
echo "<td>" . ($row['kills'] / $row['deaths']) . "</td>"; // <--- this one
echo "</tr>";
}

Answer 3

It looks like you need to group your results based on the player name. Also, you need to account for when deaths = 0. Try changing your query to -
SELECT
player,
SUM(kills) as kills,
SUM(deaths) as deaths,
CASE WHEN SUM(deaths) = 0 THEN SUM(kills)
ELSE SUM(kills)/SUM(deaths)
END as `KDR`
FROM war_kills
GROUP BY player
ORDER BY kills DESC

Answer 4

The other answers I read don't account for the fact that someone might have zero deaths. If they do, you'll get a divide by zero error.
inside your while loop,
if ($row['deaths'] == 0)
$kdr = '-';
else
$kdr = $row['kills']/$row['deaths'];
then change $row['KDR'] to $kdr