Conditional formatting php table - php

Question

I need help with a simple task, but I am stuck...
I have a database where I pull different data and I am visualizing those data on a web page.
Here is my query for getting the data:
$result = mysqli_query($mysqli, "SELECT *, DATEDIFF(nextcalibration, CURDATE()) AS days FROM tools AS dp ");
Here is my table:
<table id="table_id" class="table table-striped">
<tr>
<th>Nr</th> <th>Status</th> <th>name</th> <th>Serial</th> <th>Used At</th> <th>Owner</th> <th>Calibrated</th> <th>nextcalibration</th> <th>vendor</th> <th>days</th> <th>actions</th>
</tr>
<?php
while($user_data = mysqli_fetch_array($result))
{
echo "<tr>";
echo "<td>".$user_data['toolnr']."</td>";
echo "<td>".$user_data['status']."</td>";
echo "<td>".$user_data['toolname']."</td>";
echo "<td>".$user_data['serial']."</td>";
echo "<td>".$user_data['usedat']."</td>";
echo "<td>".$user_data['owner']."</td>";
echo "<td>".$user_data['calibrated']."</td>";
echo "<td>".$user_data['nextcalibration']."</td>";
echo "<td>".$user_data['vendors']."</td>";
echo "<td>".$user_data['days']. "</td>";
echo "<td><a href='edit.php?id=$user_data[id]'><img src='img/edit.png' ></a> | <a href='delete.php?id=$user_data[id]' onclick='return checkDelete()'><img src='img/delete.png'></a></td></tr>";
}
?>
</table>
I would like to make conditional formatting only for the last column - "days".
The idea is if the value of "days" <= 30 to become red color text.
I tried with various JS, but honestly, it did not work.

Answer 1

<table id="table_id" class="table table-striped">
<tr>
<th>Nr</th> <th>Status</th> <th>name</th> <th>Serial</th> <th>Used At</th> <th>Owner</th> <th>Calibrated</th> <th>nextcalibration</th> <th>vendor</th> <th>days</th> <th>actions</th>
</tr>
<?php
while($user_data = mysqli_fetch_array($result))
{
echo "<tr>";
echo "<td>".$user_data['toolnr']."</td>";
echo "<td>".$user_data['status']."</td>";
echo "<td>".$user_data['toolname']."</td>";
echo "<td>".$user_data['serial']."</td>";
echo "<td>".$user_data['usedat']."</td>";
echo "<td>".$user_data['owner']."</td>";
echo "<td>".$user_data['calibrated']."</td>";
echo "<td>".$user_data['nextcalibration']."</td>";
echo "<td>".$user_data['vendors']."</td>";
echo "<td>";
$days=$user_data['days'];
if($days <= 30){
echo "<span style='color:red;'>$days</span>";
}else{
echo $days;
}
echo "</td>";
echo "<td><a href='edit.php?id=$user_data[id]'><img src='img/edit.png' ></a> | <a href='delete.php?id=$user_data[id]' onclick='return checkDelete()'><img src='img/delete.png'></a></td></tr>";
}
?>
</table>

Answer 2

Would something simple like this - without JS- work?
<table id="table_id" class="table table-striped">
<tr>
<th>Nr</th> <th>Status</th> <th>name</th> <th>Serial</th> <th>Used At</th> <th>Owner</th> <th>Calibrated</th> <th>nextcalibration</th> <th>vendor</th> <th>days</th> <th>actions</th>
</tr>
<?php
while($user_data = mysqli_fetch_array($result))
{
$style_days=($user_data['days']<=30)?'style="color:red"':'';
echo "<tr>";
echo "<td>".$user_data['toolnr']."</td>";
echo "<td>".$user_data['status']."</td>";
echo "<td>".$user_data['toolname']."</td>";
echo "<td>".$user_data['serial']."</td>";
echo "<td>".$user_data['usedat']."</td>";
echo "<td>".$user_data['owner']."</td>";
echo "<td>".$user_data['calibrated']."</td>";
echo "<td>".$user_data['nextcalibration']."</td>";
echo "<td>".$user_data['vendors']."</td>";
echo "<td ".$style_days.">".$user_data['days']. "</td>";
echo "<td><a href='edit.php?id=$user_data[id]'><img src='img/edit.png' ></a> | <a href='delete.php?id=$user_data[id]' onclick='return checkDelete()'><img src='img/delete.png'></a></td></tr>";
}
?>
</table>
Of course, apply the necessary guarding for $user_data['days'] (existence, numeric..) :)