สอบถามเรื่องการ insert ข้อมูล ของรูปแบบ multiple ครับ

<?php
include 'connect_book.php';

$sql = "SELECT * FROM `bookborrow` 
INNER JOIN book ON bookborrow.bookid=book.bookid ";
$result = mysqli_query($conn, $sql);


$bookid = $_POST['bookid'];

$memberid = $_POST['memberid'];
$borrowdate = $_POST['borrowdate'];
$returndate = $_POST['returndate'];


		$sql1= "SELECT * FROM `book` where `bookid` = $bookid";
		$result1 = mysqli_query($conn, $sql1);
		$row1 = mysqli_fetch_array($result1, MYSQLI_ASSOC);

		$new_num=$row1['num']+1;

		$sq_num = "UPDATE `book` SET `num` = $new_num  where `bookid` = $bookid ";
		$result_num = mysqli_query($conn, $sq_num); 


		$sql = "INSERT INTO  `bookborrow`(`borrowid`, `bookid`, `memberid`, `borrowdate`, `returndate`, `statusbook`) VALUES (NULL, '$bookid', '$memberid', '$borrowdate', '$returndate', 0)";

		if ($conn->query($sql) === TRUE) {
			// echo "<script>";
		 //        echo "alert('บันทึกข้อมูลเรียบร้อย'); location.href = 'pj_borrowbook.php' ";
		 //    echo "</script>";
		      echo "Keep Sucsess";
		} else {
		    echo "Error: " . $sql . "<br>" . $conn->error;
		}


?>