我似乎无法弄清楚，但我的 php/mysqli 中出现错误，说明：
警告：在第 28 行的 /.../ 中为 foreach() 提供的参数无效
我的问题是如何修复上述警告，以便我可以循环插入以便能够将所有插入提供到数据库中：
<?php
ini_set('display_errors',1);
error_reporting(E_ALL);
// connect to the database
include('connect.php');
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
die();
}
$studentid = (isset($_POST['addtextarea'])) ? $_POST['addtextarea'] : '';
$sessionid = (isset($_POST['Idcurrent'])) ? $_POST['Idcurrent'] : '';
$insertsql = "
INSERT INTO Student_Session
(SessionId, StudentId)
VALUES
(?, ?)
";
if (!$insert = $mysqli->prepare($insertsql)) {
// Handle errors with prepare operation here
}
foreach($studentid as $id)
{
$insert->bind_param("ii", $sessionid, $id);
$insert->execute();
if ($insert->errno) {
// Handle query error here
}
}
$insert->close();
$query = "SELECT ss.SessionId, SessionName, StudentId
FROM
Student_Session ss
INNER JOIN Session s ON
ss.SessionId = s.SessionId
WHERE ss.SessionId = ? AND StudentId = ?";
// prepare query
$stmt=$mysqli->prepare($query);
// You only need to call bind_param once
$stmt->bind_param("ii", $sessionid, $studentid);
// execute query
$stmt->execute();
// get result and assign variables (prefix with db)
$stmt->bind_result($dbSessionId, $dbSessionName, $dbStudentId);
//get number of rows
$stmt->store_result();
$numrows = $stmt->num_rows();
//fetch the results
$stmt->fetch();
if ($numrows == 1){
echo json_encode(array('errorflag'=>false,'msg'=>"Students have been successfully added into the Assessment"));
}else{
echo json_encode(array('errorflag'=>true,'msg'=>"An error has occured, Students have not been added into the Assessment"));
}
?>