Notes

<?php
$pdo = new PDO('mysql:dbname=csy2028c;host=localhost', 'student', 'student');

if(isset($_POST['update'])){
$stmt = $pdo->prepare("UPDATE tbl_message SET msgText = :msgText, userId = :userId WHERE id = :id");
unset($_POST['update']);
echo '<pre>'; print_r($_POST); die();
if($stmt->execute($_POST)){
header('Location:addmsg.php?msg=Message Updated Successfully');
}
}

if(isset($_GET['editId'])){

// get list of users
$users = $pdo->prepare("SELECT id, fullName FROM tbl_user");
$users->execute();

$stmt = $pdo->prepare("SELECT * FROM tbl_message WHERE id = :id");
$criteria = [
'id' => $_GET['editId']
];
$stmt->execute($criteria);
$msg = $stmt->fetch();
?>
<h3>Edit Message</h3>
<form action="editmsg.php" method="POST">
<input type="hidden" name="id" value="><?php echo $_GET['editId'] ?>">
<label>Message Text : </label><textarea name="msgText"><?php echo $msg['msgText'];?></textarea><br><br>
<label>Sender : </label>
<select name="userId">
<?php
foreach ($users as $row) {?>
<option value="<?php echo $row['id']?>" <?php if($msg['userId'] == $row['id']) echo 'selected';?>>
<?php echo $row['fullName']?>
</option>
<?php }
?>
</select><br><br>
<input type="submit" name="update" value="Update">
</form>

<?php }?>

//addmsg.php

<?php
$pdo = new PDO('mysql:dbname=csy2028c;host=localhost', 'student', 'student');
if(isset($_POST['save'])){
$sql = "INSERT INTO tbl_message(msgDate, msgText, userId)
VALUES(:msgDate, :msgText, :userId)";
$stmt = $pdo->prepare($sql);
$_POST['msgDate'] = date('Y/m/d');
unset($_POST['save']);
if($stmt->execute($_POST)) echo '<p>Inserted Successfully</p>';
}

// delete a record
if(isset($_GET['delId'])){
$stmt = $pdo->prepare("DELETE FROM tbl_message WHERE id = :id");
$criteria = [
'id' => $_GET['delId']
];
if($stmt->execute($criteria)) echo '<p>Message Deleted Successfully</p>';
}
// delete a record end

// get list of users
$users = $pdo->prepare("SELECT id, fullName FROM tbl_user");
$users->execute();
?>
<h4>Add a Message</h4>
<form action="addmsg.php" method="POST">
<label>Message Text : </label><textarea name="msgText"></textarea><br><br>
<label>Sender : </label>
<select name="userId">
<?php
foreach ($users as $row) {
echo '<option value="'.$row['id'].'">'.$row['fullName'].'</option>';
}
?>
</select><br><br>
<input type="submit" name="save" value="Save">
</form>
<?php
$sql = "SELECT tbl_message.id as msgId,msgDate,msgText,fullName
FROM tbl_message JOIN tbl_user ON tbl_message.userId = tbl_user.id ORDER BY msgId";
$msg = $pdo->prepare($sql);
$msg->execute();
?>
<table border="2">
<tr>
<th>SN</th><th>Msg Date</th><th>Msg Text</th><th>Sender</th><th>Action</th>
</tr>
<?php
$sn = 1;
foreach ($msg as $row) {
echo '<tr>';
echo '<td>'.$sn++.'</td>';
echo '<td>'.$row['msgDate'].'</td>';
echo '<td>'.$row['msgText'].'</td>';
echo '<td>'.$row['fullName'].'</td>';?>
<td>
<a href="#" onClick="javascript: if(confirm('Are you sure?')){ document.location='addmsg.php?delId=<?php echo $row['msgId']?>'; }">
Delete
</a> |
<a href="editmsg.php?editId=<?php echo $row['msgId'];?>">Edit</a>
</td>
<?php echo '</tr>';
}
?>
</table>