Is there a more efficient way to compress these mysql queries?

Question

Say if I want to get 100 different users from the same table, I would have to create 100 different queries like below. I am only showing three queries as an example but you get my meaning.

I am wondering if there is a more efficient way to get as many users as I want from the same table? Important thing is that I need to have each user with their unique handle. For eg. $matrix_user_id_2, $matrix_user_id_3, $matrix_user_id_4. How can I go on about doing that?

$find_sponsor_2 = $db->prepare("SELECT user_id, filled_positions FROM matrix_2 WHERE user_id = :user_id");
$find_sponsor_2->bindValue(':user_id', 2);
$find_sponsor_2->execute();
$result_sponsor_2 = $find_sponsor_2->fetchAll(PDO::FETCH_ASSOC);
if(count($result_sponsor_2) > 0) {
  foreach($result_sponsor_2 as $row) {
    $matrix_user_id_2         = $row['user_id'];
    $filled_positions_2         = $row['filled_positions'];
  }
} else {
  $errors[] = 'User Id 2 not found in Matrix.';
}

$find_sponsor_3 = $db->prepare("SELECT user_id, filled_positions FROM matrix_2 WHERE user_id = :user_id");
$find_sponsor_3->bindValue(':user_id', 3);
$find_sponsor_3->execute();
$result_sponsor_3 = $find_sponsor_3->fetchAll(PDO::FETCH_ASSOC);
if(count($result_sponsor_3) > 0) {
  foreach($result_sponsor_3 as $row) {
    $matrix_user_id_3         = $row['user_id'];
    $filled_positions_3         = $row['filled_positions'];
  }
} else {
  $errors[] = 'User Id 3 not found in Matrix.';
}

$find_sponsor_4 = $db->prepare("SELECT user_id, filled_positions FROM matrix_2 WHERE user_id = :user_id");
$find_sponsor_4->bindValue(':user_id', 4);
$find_sponsor_4->execute();
$result_sponsor_4 = $find_sponsor_4->fetchAll(PDO::FETCH_ASSOC);
if(count($result_sponsor_4) > 0) {
  foreach($result_sponsor_4 as $row) {
    $matrix_user_id_4         = $row['user_id'];
    $filled_positions_4         = $row['filled_positions'];
  }
} else {
  $errors[] = 'User Id 4 not found in Matrix.';
} 

Answer 1

You can get all the information using 1 query. Why don't you do it like this?

 SELECT user_id, filled_positions FROM matrix_2 WHERE user_id in (2,3,4) // your ids here

and then you can iterate over the result set to check which one exists and which one doesn't.