爆炸多个用户ID

Question

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 //

Attending Field is list of users http://imageshack.us/a/img38/1425/eventsne.jpg

Trying to Echo out like this once i get username working ill do the avatar and in a table http://imageshack.us/a/img819/8210/events2d.jpg

$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'];
}

---

Just tryed KyleK 3rd suggestion

$Attending1 = array();
$Attending1 = mysql_query("SELECT * FROM Events, Users WHERE Events.Attending = Users.UserId");

$AttendingUserIds = $Attending1['Attending'];
//$AttendingExploded = explode(",", $AttendingUserIds);

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

It gives me Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource where the While starts.

Answer 1

You can do it all in just one SELECT, by joining Events and Users tables thru the find_in_set() function. That way, you will get all users which attended each event, because find_in_set() will look up the first parameter in the CSV string supplied as the second parameter. You may also want to add a WHERE to filter a specific event. And don't forget to replace the * with only the fields you need, to avoid unnecessary data traffic:

$Attending = array(); 
$Attending = mysql_query("
  SELECT * 
  FROM Events e
  INNER JOIN Users u ON find_in_set(u.UserId, e.Attending) 
");