Explode multiple user Ids

Explode multiple user Ids

Im having trouble getting explode to work I have a table field named Attending with multiple user Ids separated with commas 73,1,5 right now i can easily get user 73 to echo out but need explode for the rest, I want it to echo out each username of those 3 users or however many it ends up being. I was thinking it might be something like what i commented out with the //
$Attending1 = array(); $Attending1 = mysql_query("SELECT * FROM Events, Users WHERE Events.Attending = Users.UserId");
//$AttendingUserIds = $Attending1['Attending'];
//$AttendingExploded = explode(",", $AttendingUserIds);

//$Attending3 = array();
//$Attending3 = mysql_query("SELECT * FROM Events, Users WHERE $AttendingExploded = Users.UserId");


while ($Attending2 = mysql_fetch_array($Attending1)) {
    echo $Attending2['username'];
}