无法在新的 PHP 页面中显示搜索结果

我在另一个php页面上显示搜索结果时遇到问题。

以下是我的第二个 php 页面的 php 代码：

if (isset($_GET['bookTitle'])) {
    $bookTitle = $_GET['bookTitle'];
    $sqlSearch = "SELECT bookISBN, bookTitle, bookYear, nbc_book.catID, nbc_book.pubID, pubName,  location, catDesc, bookPrice FROM nbc_book
    LEFT JOIN nbc_category ON nbc_book.catID = nbc_category.catID
    LEFT JOIN nbc_publisher ON nbc_book.pubID = nbc_publisher.pubID LIKE CONCAT('%', bookTitle, '%') 
    WHERE bookTitle = " . $_GET['booktitle'] ;
    echo "string";
    $resultSearch = mysqli_query($conn,$sqlSearch) or die (mysql_error());
    while ($row = mysqli_fetch_assoc($resultSearch)){
        $category = $row['catDesc'];
        $bookTitle = $row['bookTitle'];
        $publisherName = $row['pubName'];
        $bookYear = $row['bookYear'];
        $bookPrice = $row['bookPrice'];
        echo "Result found!";
    }
}else{
    echo "Result not found!";
}
mysqli_free_result($resultSearch);
mysqli_close($conn);

这是我得到的错误：

Result not found!
Notice: Undefined variable: querySearch in /
Warning: mysqli_free_result() expects parameter 1 to be mysqli_result, null given in /

谁能帮我解决我的问题。如果有人能帮助我解决这个问题，我会很高兴。