line-breaks between every 2 row - php

Question

I'm quit new with mysql, and php but everytime i'm learning.
For a friend of my I'm building a website with a small pricing-list on it.
The prices are from a database, but I now want to create a empty line bewtween the 2nd and the 3th line, but I don't know how to do that.
I use the following code to receive the information from the database;
<table id="nails" class="prijzen">
<thead>
<tr>
<th>Nails</th>
<th>Price first visite</th>
<th>Regular price</th>
</tr>
</thead>
<?php
// while ($row = $queryNails->fetch_assoc()) {
$i = 0;
while ($row = $regularNails->fetch_assoc())
{
if($i%3 == 0)
{
echo "<tr class='even'>";
echo "<td>" . $row['name'] ."</td>";
echo "<td>" . $row['prijs'] ."</td>";
echo "<td>" . $row['actie_prijs'] ."</td>";
echo "</tr>";
}
else
{
echo "<tr>";
echo "<td>" . $row['name'] ."</td>";
echo "<td>" . $row['prijs'] ."</td>";
echo "<td>" . $row['actie_prijs'] ."</td>";
echo "</tr>";
}
$i++;
?>
<tbody>
<?php
}
?>
</tbody>
</table>
<br>
I now have every odd-line a styling, but that is not something I like. I would like to create a sort of group of the output.
Hope someone can help me with that. If more information is needed, please let me know.

Answer 1

Please stop suggestion to enter a <br /> in between lines. That's not gonna work at all, tables-101: Everything not placed in a td will be placed in before the table. So all you get is a bunch of empty lines before the whole table.
The code is allready there (if you want it before every 3rd row:
if($i%3 == 0)
{
// The code right here will only run when $i / 3 is exactly 0 (3,6,9,etc)
echo '<tr><td colspan="3">Blank line</td></tr>';
echo "<tr class='even'>";
echo "<td>" . $row['name'] ."</td>";
echo "<td>" . $row['prijs'] ."</td>";
echo "<td>" . $row['actie_prijs'] ."</td>";
echo "</tr>";
}
If you only want it once before the 3rd row, make this the first code in your while:
if($i==3){ echo '<tr><td colspan="3">Blank line</td></tr>'; }
The % is modulus. It gives you how much is left after getting the max amount of whole divisions:
echo 1 %3 = 1;
echo 2 %3 = 2;
echo 3 %3 = 0; // exactly dividable by 3
echo 4 %3 = 1;
echo 5 %3 = 2;
echo 6 %3 = 0; // exactly dividable by 3