Limiting what content is displayed from MySQL/ PHP - php

Question

I'm building an interactive timeline that loads in films and calculates the difference between their release dates, thus displaying "days" where there isn't any film release to create a timeline effect. However I have some films that are released on the same date. I don't want to repeat the date for these films over and over again, rather just display the date for the first film in like a group effect.
I have manipulated an if statement that loops through the table and checks whether the date is the same as the previous row's date.
http://ignitethatdesign.com/CheckFilm/test_search.php
However how would I use PHP to only display the date for the first film in a group of films with the same date?
I'm using a complex loop system, here is the full code
<?php
$last_value = null;
echo "<div class=\"timeline\">";
$pNumber = 0;
while ($row = mysql_fetch_assoc($sql)) {
if (!is_null($last_value)) {
$pNumber++;
$a = new DateTime($row['FilmRelease']);
$film_date = $row['FilmRelease'];
$film_name = urldecode($row['FilmName']);
$film_desc = urldecode($row['Synopsis']);
echo "<div id=\"t".$pNumber."\"><p class=\"everyday\">".$film_name."</div>";
if (empty($film_desc)) {
echo "<div id=\"b".$pNumber."\" style=\"font-size:12px;\">No film information for ".$film_name."</div>";
}
else
{
echo "<div id=\"b".$pNumber."\" style=\"font-size:12px;\">".$film_desc."</div>";
}
?> <script type="text/javascript">
$("#b<?php echo $pNumber ?>").hide();
$("#t<?php echo $pNumber ?>").click(function() {
$("#b<?php echo $pNumber ?>").fadeToggle("slow");
});
</script>
<?php
$interval = $a->diff(new DateTime($last_value));
//echo $interval->format('%d days');
$b = new DateTime($last_value);
$i = 0;
}
if ($b == $a)
{
echo "same date as above";
} else
{
echo "This date is different";
}
$howManydays = $interval->days;
for ( $i; $i < $howManydays; $i++) {
echo "<p class=\"day\"></p>";
}
$last_value = $row['FilmRelease'];
}
echo "<div id=\"end\"></end>";
echo "</div>";
?>
Any help would be greatly appreciated :)

Answer 1

Simple example:
$lastDate = null;
while (...) {
$currentDate = date('Y-m-d', strtotime($film['date']));
if ($currentDate != $lastDate) {
echo "<h1>$currentDate</h1>";
}
$lastDate = $currentDate;
// output film details
}
This will give you something like:
2012-04-01
Film A
Film B
2012-04-02
Film C
2012-04-05
Film D
Film E