Joywork/ajax/addActivities.php

<?php

require_once($_SERVER['DOCUMENT_ROOT'] . "/config.php");

if ($_SESSION['id'] && $_POST['id'] && is_numeric($_POST['id']) && $_POST['instance']) {

    $post = clearInputData($_POST);
    if ($id = $post['id']) {
        if ($post['instance'] == "objects") {

            $sql = "DELETE FROM `objects_activities` WHERE `object_id` = '".$id."'";
            mysql_query($sql);

            if (!empty($post['activities'])) {
                if (is_array($post['activities'])) {
                    $sql_a = [];
                    foreach($post['activities'] as $key => $activity_id) {
                        $sql_a[] = "('$id', '$activity_id')";
                    }
                    if (count($sql_a) > 0) {
                        $sql = "INSERT INTO `objects_activities` (`object_id`, `activity_id`) VALUES " . implode(', ', $sql_a);
                        mysql_query($sql);
                    }
                } else if (is_numeric($arr_activities)) {
                    $sql = "INSERT INTO `objects_activities` (`object_id`, `activity_id`) VALUES ('$id', '$post[activities]')";
                    mysql_query($sql);
                }
            }

            $output = array();
            $sql = "SELECT object.activity_id AS id,
                       activities.name AS name, 
                       activities.color AS color 
                       FROM objects_activities AS object
                       LEFT JOIN activities AS activities ON activities.id = object.activity_id
                       WHERE object.object_id=$id";

            $rez = mysql_query($sql);
            if (mysql_num_rows($rez) > 0) {
                while($row = mysql_fetch_array($rez)) {
                    if ($row['id'] && $row['name']) {
                        $output[] = [
                            'id' => $row['id'],
                            'name' => $row['name'],
                            'color' => $row['color']
                        ];
                    }
                }
            }

            echo json_encode($output);
        } else if ($post['instance'] == "clients") {

            $sql = "DELETE FROM `clients_activities` WHERE `client_id` = '".$id."'";
            mysql_query($sql);

            if (!empty($post['activities'])) {
                if (is_array($post['activities'])) {
                    $sql_a = [];
                    foreach($post['activities'] as $key => $activity_id) {
                        $sql_a[] = "('$id', '$activity_id')";
                    }
                    if (count($sql_a) > 0) {
                        $sql = "INSERT INTO `clients_activities` (`client_id`, `activity_id`) VALUES " . implode(', ', $sql_a);
                        mysql_query($sql);
                    }
                } else if (is_numeric($arr_activities)) {
                    $sql = "INSERT INTO `clients_activities` (`client_id`, `activity_id`) VALUES ('$id', '$post[activities]')";
                    mysql_query($sql);
                }
            }

            $output = array();
            $sql = "SELECT client.activity_id AS id,
                       activities.name AS name, 
                       activities.color AS color 
                       FROM clients_activities AS client
                       LEFT JOIN activities AS activities ON activities.id = client.activity_id
                       WHERE client.client_id=$id";

            $rez = mysql_query($sql);
            if (mysql_num_rows($rez) > 0) {
                while($row = mysql_fetch_array($rez)) {
                    if ($row['id'] && $row['name']) {
                        $output[] = [
                            'id' => $row['id'],
                            'name' => $row['name'],
                            'color' => $row['color']
                        ];
                    }
                }
            }

            echo json_encode($output);
        }
    }
}