My Longest AJAX File

<?php
    include("../../php/fw.php"); $f = new PTracker();

    // Initialize Variables
    $db = $f->Connect();
    $prefix = $f->GetOpt("db", "tablePrefix");

    $title = $_POST["title"];
    $authorID = $_POST["authorID"];
    $authorUsername = $_POST["authorUsername"];
    $projectID = $_POST["projectID"];
    $projectName = $_POST["projectName"];
    $priorityID = $_POST["priorityID"];
    $priorityName = $_POST["priorityName"];
    $priorityColor = $_POST["priorityColor"];
    $stateID = $_POST["stateID"];
    $stateName = $_POST["stateName"];
    $type = $_POST["type"];
    $assignedTo = $_POST["assignedTo"];
    $assignedToID = $_POST["assignedToID"];

    $jsonReturn = array();
    $jsonReturn["error"] = 50;
    $jsonReturn["errorMessage"] = "okay";

    // Create queries.
    $checkTitleQuery = "select * from ".$prefix."tickets where `title` = '$title' where `projectID` = '$projectID';";
    $updateTicketCount = "update ".$prefix."projects set `tickets` = `tickets` + 1 where `id` = '$projectID';";
    $insertQuery = "insert into ".$prefix."tickets (
        `title`, `authorID`, `authorUsername`, `projectID`, `projectName`, `priorityID`,
        `priorityName`, `priorityColor`, `stateID`, `stateName`, `type`, `assignedTo`, `assignedToID`) values (
        '$title', '$authorID', '$authorUsername', '$projectID', '$projectName', '$priorityID', '$priorityName',
        '$priorityColor', '$stateID', '$stateName', '$type', '$assignedTo', '$assignedToID' );";

    // Perform Checks
    $res = $db->query($checkTitleQuery);
    if (mysqli_error($db) != "") {
        $jsonReturn["error"] = 100;
        $jsonReturn["errorMessage"] = mysqli_error($db);
        die(json_encode($jsonReturn));
    }
    if ($res->num_rows > 0) {
        $jsonReturn["error"] = 101;
        $jsonReturn["errorMessage"] = "That ticket already exists.";
        die(json_encode($jsonReturn));
    }

    // Insert into the table.
    $db->query($insertQuery);
    if (mysqli_error($db) != "") {
        $jsonReturn["error"] = 100;
        $jsonReturn["errorMessage"] = mysqli_error($db);
        die(json_encode($jsonReturn));
    }

    // Update the ticket count.
    $db->query($updateTicketCount);
    if (mysqli_error($db) != "") {
        $jsonReturn["error"] = 100;
        $jsonReturn["errorMessage"] = mysqli_error($db);
        die(json_encode($jsonReturn));
    }

    // All was successful.
    die(json_encode($jsonReturn));
?>