为什么UPDATE会创建新记录？

Question

For event listing page. After inserting record into db I capture last ID with

//Store ID[LAST]
    $ID = mysqli_insert_id($db);

Next the page shows event formatted for easy reading. Then user can hold or approve item for publication with 2 buttons: Draft, Publish. I use submits buttons for each:

//Check ID value (use for testing)
    echo "<p>ID = ".$ID."</p>
";

    echo "<form action='".$_SERVER['PHP_SELF']."' method='GET'>
    <input type='submit' name='submitDraft' value='Draft' />
    <input type='submit' name='submitPublish' value='Publish' />
    </form>";

Now I use conditional to update record according to button chosen. (Note connect.php is include that manages passcodes and connection statement.)

if (isset($_REQUEST["submitDraft"])) {
    include('includes/connect.php');
    $sql="UPDATE sessions SET postit='0' WHERE ID='$ID'";
    if (mysqli_query($db, $sql)) {
            echo "Record updated successfully";
        } else {
            echo "Error updating record: " . mysqli_error($db);
        }

        mysqli_close($db);
    }

    if (isset($_REQUEST["submitPublish"])) {
    include('includes/connect.php');
    $sql="UPDATE sessions SET postit='1' WHERE ID='$ID'";
    if (mysqli_query($db, $sql)) {
            echo "Record updated successfully";
        } else {
            echo "Error updating record: " . mysqli_error($db);
        }

        mysqli_close($db);
    }

My problem is UPDATE statement adds new record to table but should update same record. What is my mistake please.

Answer 1

I solve this. Because form resubmit whole page, insert statement is run each time and add new record. This record also get update so appear like UPDATE is add new record. Really INSERT make new record and UPDATE change 'postit' field in same time. To fix I add conditional if $_REQUEST not equal submitDraft or submitPublish then INSERT, else it skip over INSERT. Also I just see same kind of answer from @Jay Patel and @SBA. Thank you to both