How to save multiple checkboxes values in different rows of database

I am working on a checkbox table, the submitted data should be saved in the mysql database. There are two columns in the table, auto-increment Id and another one for saving the values of the checkbox.

Currently it is only saving one value at a time even when I select multiple, only the latest one gets saved. Here's the code:

report.php

<?php


$active = "report";
require_once 'pages/header.php';
require_once './functions/schema-functions.php';

$course = Schema::getCourse();
$objective = Schema::getObjective();
?>




<form id="addReport" action ='./functions/report-functions.php' method="post">

<table id="table1" class="table">
    <?php
    echo '<tr><th>Objectives</th>';
    for ($i = 0; $i < count($course); $i++) {
        echo '<th id = "rotate1">'. $course[$i]->commonName . '</th>';            
    }
    echo '</tr>';

    for ($y = 0; $y < count($objective); $y++) {
        echo '<tr><th class=row-header>'.$objective[$y]->objective.'</th>';

    for ($x = 0; $x < count($course); $x++) {

        echo "<td><input name='check[]' type=checkbox value=c".$course[$x]->courseId."-o".$objective[$y]->objectiveId." id=checked></td>";

        }
        echo '</tr>';
    }
    ?>

</table>
<input type="submit" name= "submit" value= "Submit"/>

report-functions.php

<?php


 require_once 'db-connect.php';

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


$conn = DatabaseConnection::getConnection();
    $conn->beginTransaction();
    if(isset($_POST['check'])){
   foreach($_POST['check'] as $value){
    $sql = $conn->prepare("INSERT INTO Report (ColRow) VALUES 
 ('$value')");
  }
    if ($sql->execute(array( ':checked' => $checked))) {
        $conn->commit();
        return true;
    } else {
        $conn->rollback();
        return false;
    }

   }
   }
   }
    ?>

I want to save multiple selected checkboxes in different rows of the database and after submit, I want to display the table again with the boxes being checked and the user should be able to make the checks and submit the data again.