而在里面虽然PHP

Question

We're trying to put a while inside a while loop. The first while is run through and the results are displayed in a list (139, 140, 141). The list for the second while only displays one value (1ste troop). These are the results:
139
1ste troop
140
141

So it seems that the second while is only executed once. What can I do to fix this?

echo "<ul>";            
            while($user = $allUsersintroops->fetch_assoc())
            {

                if($user['userid'] == $_SESSION['userid'])
                {   
                    echo "<li>" . $user['troopid'].  " </li>";

                    while ($mytroops = $alltroops->fetch_assoc()) 
                    {
                        if($user['troopid'] == $mytroops['troopid'])
                        {
                            echo "<li>" . $mytroops['description'].  " </li>";
                        }
                    }
                }   
            }           
echo "</ul>";

Answer 1

The inner loop stops once fetch_assoc returns false... but that indicates the end of all found results and it doesn't have any rows left for the next iteration.

You should collect all the rows from $alltroops into an array once, then iterate over that:

echo "<ul>";
$allTroopsList = array();
while ($mytroops = $alltroops->fetch_assoc()) {
  $allTroopsList []= $mytroops;
}
while($user = $allUsersintroops->fetch_assoc()) {
  if($user['userid'] == $_SESSION['userid']) {   
    echo "<li>" . $user['troopid'].  " </li>";

    foreach($allTroopsList as $mytroops) {
      if($user['troopid'] == $mytroops['troopid']) {
        echo "<li>" . $mytroops['description'].  " </li>";
      }
    }
  }   
}           
echo "</ul>";

Additionally, you should consider adding some filtering to your $allUsersintroops query, because you are only using a part of the the returned rows, which means the rest of the rows are sent from the DB to your code for no reason, wasting time and bandwidth.