Questa è un'idea:
<?php
$sql = "SELECT * FROM posts ORDER by post_date DESC";
$res = mysql_query($sql);
$previous_date = "";
while($post = mysql_fetch_assoc($result)){
//here goes the date
if($post['post_date'] != $previous_date){
echo $post['post_date'];
echo "<br>--------------------<br>";
$previous_date = $post['post_date'];
}
//here goes the post
echo "Post:{$post['title']}<br>";
}
?>
