循环中的SQL注入不起作用

        <?php
include '../connectdb.php';


$sqlNAME = 'INSERT INTO group_general (group_name)
VALUES (?)';

if($statementNAME = $connect->prepare($sqlNAME)) {

    $statementNAME->bind_param(

        "s",
        $_POST['groupName']
        );

    $statementNAME->execute();
}

$groupName = $_POST['groupName'];

$selectGROUPID = 'SELECT * FROM group_general WHERE group_name = "'.$groupName.'"';

$resultGROUPID = $connect->query($selectGROUPID);

if ($resultGROUPID->num_rows > 0) {
    $rowGROUPID = $resultGROUPID->fetch_assoc();
}

/* The error is somewhere around here~ish */

for ($x=0; $x<sizeof($_POST['addedUsers']); $x++) { 
    $rowUSERS[$x] = $_POST['addedUsers'][$x];

    $sqlUSERS = 'INSERT INTO group_users (user_name, group_id)
    VALUES ("'.$rowUSERS[$x].'", "'.$rowGROUPID['group_id'].'")';

    if($statementUSERS = $connect->prepare($sqlUSERS)) {


    if ($statementUSERS->execute()) {

        echo "Successfully created the group!";

    }
     else {
    echo "Failed to create the group...";
}
}
}
?>

So my issue is whenever a user selects multiple people (so the array $rowUSERS[] becomes more than only the 0 value), it only inserts the first selected user into the DB while it actually should loop through every selected user and insert it one by one. I really don't know what I did wrong here. Can you please look at it and help me?

Edit:

I fixed it, for some reason my group_id row in the DB had a primary key.

Sorry for bothering you guys,

~Lars