mySQL: Assigning an auto increment ID number to a double select query

Question

I am creating a program where data I select from one table is being randomly grouped. The RegistrationID number from each group is saved into another table (as a foreign key) and every group member is assigned a groupID that is auto incremented with every new group created.

$GroupSize = $_POST['groupsize'];

//Connect to the Server+Select DB
$con = mysqli_connect($host, $user, $password, $dbName) or die("Nope");

if (isset($_POST['create'])) {

//assign group id to groups created
//insert groupinformation to table from userInformation
      $query = "SELECT  RegistrationId FROM (Select * from userInformation order by RAND() LIMIT ".$GroupSize.") INTO groupInformation";
      $result = mysqli_query($con, $query) or die ("query failed" . mysqli_error($con));


//display group and information
    echo "<table border='1' >";
    echo "<tr><th>RegId</th><th>Name</th><th>Address</th><th>Email</th></tr>";
    while (($row = mysqli_fetch_row($result)) == true) {
        echo "<tr><td>$row[0]</td><td>$row[1]</td><td>$row[2]</td><td>$row[3]</td></tr>";
    }
    echo "</table>";

//if group is less than 2 create error message

}

mysqli_close($con);

My problem is that I cannot assigned the GroupId to the extracted results because auto incremented numbers cannot be copied. This is my error:

query failed Every derived table must have its own alias

Here are my Table schemas

Answer 1

Let GroupId autoincrement,then create one more column RandomGroupId in groupInformation , then paste the query:

INSERT INTO groupInformation(RandomGroupId,RegistrationId) 
SELECT randomRegistrationId,RegistrationId 
FROM (Select *,RAND() AS randomRegistrationId 
      FROM userInformation ORDER BY randomRegistrationId LIMIT ".$GroupSize."
      ) AS j