PHP MySQLi not updating - php

Question

I have been trying to make a form where I can update two fields one field is going be admin_welcomebox and admin_author and I'm trying update it by the id so here go my code
<div class="col-lg-6">
<div class="panel panel-color panel-inverse">
<div class="panel-heading">
<h3 class="panel-title">Welcome Box Update</h3>
</div>
<?php
if(isset($_POST["submit"])){
$servername = "localhost";
$username = "trres";
$password = "sss";
$dbname = "txxxs";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "UPDATE admin_news SET welcomebox = '{$admin_news}' SET author = {$admin_author} id='{$id}'";
if ($conn->query($sql) === TRUE) {
echo "<h4 class='bg-success'>You have updated admin welcome box.</h4>";
} else {
echo "<script type= 'text/javascript'>alert('Error: " . $sql . "<br>" . $conn->error."');</script>";
}
$conn->close();
}
?>
<div class="panel-body">
<form method="post" action="">
<div class="form-group">
<label for="welcomebox">Welcome Box</label>
<textarea type="text" name="welcomebox" id="welcomebox" placeholder="Enter Your Message" class="form-control"></textarea>
</div>
<div class="form-group">
<label for="author">Author Name</label>
<input type="text" name="author" id="author" placeholder="Author Name" class="form-control" / >
</div>
<div class="form-group text-right m-b-0">
<button class="btn btn-primary waves-effect waves-light" type="submit" name="submit" id="submit">
Update Info
</button>
</div>
</form>
</div>
</div>
</div>
When I try update it just refresh the page nothing else.

Answer 1

Your query has invalid syntax. This is wrong:
UPDATE admin_news SET welcomebox = '{$admin_news}' SET author = {$admin_author} id='{$id}'
The right MySQL syntax for UPDATE is
UPDATE admin_news SET welcomebox = 'value', author = 'value' WHERE id='id'
More in the MySQL manual
Moreover, where do you define $admin_news, $admin_author and $id? I do not see any variable definition in your code.

Answer 2

You didn't define $admin_news ,$admin_author and $id as well. define first.
Try this code :-
<div class="col-lg-6">
<div class="panel panel-color panel-inverse">
<div class="panel-heading">
<h3 class="panel-title">Welcome Box Update</h3>
</div>
<?php
if(isset($_POST["submit"])){
$servername = "localhost";
$username = "trres";
$password = "sss";
$dbname = "txxxs";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$id=$_POST['id'];
$admin_news=$_POST['welcomebox'];
$admin_author=$_POST['author'];
$sql = "UPDATE admin_news SET welcomebox = '$admin_news', author = $admin_author where id=$id";
if ($conn->query($sql) === TRUE) {
echo "<h4 class='bg-success'>You have updated admin welcome box.</h4>";
} else {
echo "<script type= 'text/javascript'>alert('Error: " . $sql . "<br>" . $conn->error."');</script>";
}
$conn->close();
}
?>
<div class="panel-body">
<form method="post" action="">
<input type="hidden" name="id" value="<?php echo $id; ?>" /> <!-- put here your id -->
<div class="form-group">
<label for="welcomebox">Welcome Box</label>
<textarea type="text" name="welcomebox" id="welcomebox" placeholder="Enter Your Message" class="form-control"></textarea>
</div>
<div class="form-group">
<label for="author">Author Name</label>
<input type="text" name="author" id="author" placeholder="Author Name" class="form-control" / >
</div>
<div class="form-group text-right m-b-0">
<button class="btn btn-primary waves-effect waves-light" type="submit" name="submit" id="submit">
Update Info
</button>
</div>
</form>
</div>
</div>
</div>