AJAX删除数据库条目

I am new to AJAX (and website development in general) and I am having trouble deleting a database entry in wordpress using jQuery and AJAX.
The user selects an entry in a table and clicks a button to delete it. The table is created using datatables plugin and extensive coding to make it work the way I need it to.
the jQuery code is in functions.php and the actual query is in a file on the server.
I have been using this how to delete records from database with an Ajax as a baseline for the code. Also, note that I am using wordpress My problem is that it does not seem to delete the entry from the database.

Here is the code in functions.php:

var GroupID2Del = dt.row({
        selected: true
    })
    .data()[23];
if (confirm('Are you sure you want to delete this row?')) {
    jQuery.ajax({
        type: 'POST',
        url: '/wp-content/AJAX/ViewTable_DeleteEntry.php',
        data: 'groupid=' + GroupID2Del,
        success: function(data) {
            dt.row({
                    selected: true
                })
                .remove();
            jQuery('#UserTable')
                .DataTable()
                .draw();
            alert(data);
        }
    });
}

GroupID2Del is how I am getting the id for it the selected row in the table. I am then removing the row from the table itself. The row does get removed.

Here is the ViewTable_DeleteEntry.php

<?php
    $dataPosted = $_POST['groupid'];
    $sql = ('delete from wp_piic_formmaker_submits WHERE form_id = 13 and group_id =' . $dataPosted);
    mysql_query($sql);
    $count = mysql_affected_rows();
    print $count; 
?>

alert in function.php provides the correct sql, but the $count is empty since it does not actually delete anything.

Please Try This:

 var myKeyVals = { groupid : GroupID2Del}
    jQuery.ajax(
      {
         type: 'POST',
         url: '/wp-content/AJAX/ViewTable_DeleteEntry.php',
         data: myKeyVals,
         success: function(data)
         {
            dt.row({selected: true }).remove();                                             
            jQuery('#UserTable').DataTable().draw();
            alert(data);
         }
     });

AND

$dataPosted = $_POST['groupid'];
if($dataPosted != ''){
$sql = ('delete from wp_piic_formmaker_submits WHERE form_id = 13 and group_id ='.$dataPosted);
    mysql_query($sql); 

$count = mysql_affected_rows();
} else {
echo 'Blank Record';
}

So the problem was that I am not connected to the database, so i added the following lines to at the beginning of the php file

<?php
    $servername = "localhost";
    $username = "username";
    $password = "password";
    $dbname = "dbname";

    mysql_connect($servername, $username, $password, $dbname) or die("Connection failed");
    mysql_select_db($dbname) or die("No Database found.");
?>

function delete_row()
{   
    $id=$_REQUEST['post_id'];
    $t_response = array('status'=>4,'msg'=>'Invalid Parameter');
    if( $id == false ) {
        $t_response = array('status'=>3,'msg'=>'Invalid ID');

    } else {
        global $wpdb;
         $remove = $wpdb->query("DELETE FROM wp_posts WHERE ID = ".$id);
        if($remove) {
            $t_response = array('status'=>1,'msg'=>'Record Deleted');
        } else {
            $t_response = array('status'=>2,'msg'=>'Error Occure While Deleting Your Record Deleted');
        }
    }
    echo json_encode($t_response);
    die();
}

Ajax file

$.ajax({
    url: custom_js.ajax,
    type: 'POST',
    dataType: "json",
    data: {
        'action': 'my_action',
        'post_id': id
    },
    success: function(data) {
        if (data.status == 1) {
            console.log(data);
            s_row.remove();
        } else {
            alert(data.msg);
        }
    }
});