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Question

Edited:

So, I have multiple checkboxes. My goal is to insert checkbox value in MySQL if is checked, and to delete checkbox value from MySQL if is not checked. Everything works fine except deleting the value. PHP doesn't know which checkboxes are "unchecked". Any idea?

So far I have this:

if(isset($_POST['values']))
{
    foreach($_POST['values'] as $checked)
    {
        $query5 = ("
        INSERT INTO ecust_user_contract (fk_contract, fk_cust_user)
        VALUES ('".$checked."','".$username_u."')
        ");
        $result5 = mysqli_query($conn,$query5); 
    }
}
if(!isset($_POST['values']))
{
    foreach($_POST['values'] as $unchecked)
    {
        $query5 = ("
        INSERT INTO ecust_user_contract (fk_contract, fk_cust_user)
        VALUES ('".$unchecked."','".$username_u."')
        ");
        $result5 = mysqli_query($conn,$query5);
    }
}

Answer 1

Assuming that you have used POST method for form submission, you can do something like this:

html:

<input type="checkbox" name="values[]" value="val1">
<input type="checkbox" name="values[]" value="val2">
<input type="checkbox" name="values[]" value="val3">

php:

if(isset($_POST['values'])) {
 foreach($_POST['values'] as $checked){
 mysqli_query("insert into tablename(value) values($checked)");
  }
 }else{
 // use Delete query
  }