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Not working properly. Grabbing name.


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OK so guys and gals, I'm writing a chat program and I want it to display a username in the user online box. So, i reached this code (which works)..

		$stmt = $pdo->prepare("SELECT * FROM `joined_chats` WHERE room_id = ? AND CURRENT_TIMESTAMP() <= date_expire GROUP BY user_id;");
		while ($row = $stmt->fetch()) {
   			 echo "<li>".$row['user_id']."</li>";

So, this shows the user id's of all users.. but I want it to be usernames, so i changed it to...

		$stmt = $pdo->prepare("SELECT * FROM `joined_chats` WHERE room_id = ? AND CURRENT_TIMESTAMP() <= date_expire GROUP BY user_id;");
		while ($row = $stmt->fetch()) {
			$stmt = $pdo->prepare("SELECT * FROM users WHERE user_id=?");
			$user = $stmt->fetch();
   			 echo "<li>".$user['name']."</li>";

However now It only displays one user...

What am I doing wrong guys and gals? Been a few months since i last coded php.

Edited by oz11
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  • oz11 changed the title to Not working properly. Grabbing name.
  • Solution

Overwriting your first $stmt object with the second one perhaps?

A couple of DON'TS for you...

  • Don't use SELECT * - specify just the columns you need. That makes it more efficient and people like us can see what the query is doing.
  • Don't run queries inside loops like that. Use a single query with a JOIN
SELECT jc.user_id
     , u.name
FROM joined_chats jc
     JOIN users u ON jc.user_id = u.user_id
WHERE jc.room_id = ?
      AND NOW() <= jc.date_expire
ORDER BY user_id


  • Great Answer 1
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I'd criticise you for those too.

Yes, you could have used "... FROM joined_chats jc, users u WHERE jc.user_id = u.user_id ..." but I dislike that method for several reasons.

  • it confuses the row selection conditions with join conditions and obfuscates the structure of the query and its table relationships.
  • That syntax can't be used for LEFT/RIGHT OUTER JOINS. Even if you want a cartesian join with no conditions, use tableA CROSS JOIN tableB to be explicit about what is required and you haven't just forgotten the WHERE bits.
  • I have found queries using WHERE JOINS run slower than the same query using explicit JOIN .. ON syntax.
  • Thanks 1
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