我正在尝试为我从userinformation创建的每个组分配一个id号，并将其保存到groupinformation中。我不断得到错误：
列计数与第1行的值计数不匹配
我不确定是否应该增加groupid。如果通过php或mysql。有人建议我创建一个数组来增加groupid，但我不知道如何开始。
我的table是：
groupinformation=groupid（主键，自动递增），registrationid（外键）
userinformation=registrationid（主键，自动递增）、姓名、电子邮件、地址

$GroupSize = $_POST['groupsize'];

$con = mysqli_connect($host, $user, $password, $dbName) or die("Nope");

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

//assign group id to groups created
//insert RegistrationId into groupinformation from records randomly selected from userInformation,  group Id must increment by every group created in groupinformation

//$query ="Select RegistrationId from userInformation order by RAND() LIMIT ".$GroupSize;
   $query = "INSERT INTO groupInformation SELECT RegistrationId FROM (SELECT RegistrationId FROM userInformation ORDER BY RAND() LIMIT ".$GroupSize.") as res";

    $result = mysqli_query($con, $query) or die ("query failed " . mysqli_error($con));

//unsure how to use this array
    while (($row = mysqli_fetch_row($result)) == true) {
        echo $row[0].'<br>';

    }