how do I uncheck values from my database? - php

Question

With my code here, if the user checks a check box beside one of the names
the name gets saved into my review_shared table.
I'm trying to have my code so that if a box is unchecked, the name will be REMOVED from the review_shared table.
Does you know how I can do this, or where I should start ? So, If Paul Thompson and/or Dan Frain are unchecked, they will be removed from my review_shared table.
<?php
//here we want to save the checked contacts to the review_shared table ; that is,
//who the user wants to share reviews with
if(!empty($_POST['check_contacts'])) {
foreach($_POST['check_contacts'] as $check) {
//$check="";
//if the contact in review_shared is already checked, we don't want to save it multiple times
$already_checked = "SELECT * from review_shared WHERE user_id = '$user_id' AND contact_id = '$check' AND review_id = " .$_GET['id'];
$already_checked_result=mysqli_query($con,$already_checked);
$num_rows = mysqli_num_rows($already_checked_result);
if($num_rows >= 1) {
echo "This is already a contact";
}
else if ($num_rows < 1) {
//$_GET['id'] is the current review for which contacts are being edited, we are checking a contact to share that review with
$insert_review_shared_command = "INSERT INTO review_shared VALUES(NULL," .$_GET['id']. ", '$user_id','$check')";
//we want to save the checked contacts into the review_shared table
$insert_into_review_shared_table = mysqli_query($con,$insert_review_shared_command);
}
}
}
$con->close();
?>

Answer 1

The unique way to achieve what you need is to
delete all the entries
insert the checked options
While saving your form data.
To delete all the previous entries do something like this
$sql = "DELETE FROM review_shared WHERE your-conditions";
This because when you are posting checkboxes, you will receive ONLY the checked ones on the server side. Those ones are the data you need to store.

Answer 2

Thanks to Simone Cabrino above, I simply added this into my code :
$already_checked = "DELETE from review_shared WHERE user_id = '$user_id' AND review_id = " .$_GET['id'];
mysqli_query($con,$already_checked);