how to store multiple checkbox data in database - database

Question

i am trying to insert multiple checkbox data in my database but having a little bit problem. When i am trying to insert checkbox data it inserts only id and nothing else.
Here is my full code:-
<?php
include("config.php");
if(isset($_POST['save'])){
$contact_sms = $_POST['contact_sms'];
$check[] = $_POST['check'];
$firm_name = $_POST['firm_name'];
var_dump($firm_name);
$checkbox = $_POST['check'];
for($i=0;$i<count($checkbox);$i++){
$bulksms="INSERT INTO bulk_sms (sent_sms,firmname_sms,contact_sms) VALUES('".$checkbox[$i]. "','".$row['firm_name']. "','$contact_sms')";
$smsquery=mysqli_query($conn, $bulksms);
}
}
$sql="SELECT * FROM inventory_details where status ='0' AND role='0' ORDER BY position ASC, role ASC, visiter DESC limit 0,100";
$query=mysqli_query($conn, $sql);
?>
<form method="post" action="" id="msform">
<?php
$i=0;
while($row=mysqli_fetch_assoc($query)){
$id = $row['id'];
$firm_name = $row['firm_name'];
?>
<div class="col-md-4">
<input type="text" class="form-control" name="id_sms" value="<?php echo $id;?>">
</div>
<div class="col-md-6">
<input type="text" class="form-control" name="firm_name[]" value="<?php echo $firm_name;?>">
</div>
<div class="col-md-2">
<input type="checkbox" id="checkItem" name="check[]" value="<?php echo "$id"; ?>">
</div>
<?php
$i++;
}
?>
<input type="text" class="form-control" name="contact_sms" placeholder="Contact Number..">
<button type="submit" class="btn btn-success" name="save">Send</button>
</form>
when i click on Send button , it only stores idinside the field sent_sms and nothing in field firm_name. Please help me out. I am poorly trapped in it.
Updated code:
if(isset($_POST['save'])){
$contact_sms = $_POST['contact_sms'];
$check[] = $_POST['check'];
$firm_name = $_POST['firm_name'];
var_dump($_POST);
$checkbox = $_POST['check'];
for($i=0;$i<count($checkbox);$i++){
$bulksms="INSERT INTO bulk_sms (sent_sms,firmname_sms,contact_sms) VALUES('".$checkbox[$i]. "','".$firm_name[$i]. "','$contact_sms')";
$smsquery=mysqli_query($conn, $bulksms);
}
}

Answer 1

I think $row['firm_name'] is not defined, try changing this line:
$bulksms="INSERT INTO bulk_sms (sent_sms,firmname_sms,contact_sms) VALUES('".$checkbox[$i]. "','".$row['firm_name']. "','$contact_sms')";
to this:
$bulksms="INSERT INTO bulk_sms (sent_sms,firmname_sms,contact_sms) VALUES('".$checkbox[$i]. "','".$firm_name. "','$contact_sms')";
Also it should be noted that you have not sanitized the inputs, leaving your site vulnerable to sql injection. You should always sanitize user input, and it is highly recommended to use prepared statements when inserting into the database.