mysql使用插入按钮从现有表中插入记录

Question

对不起，如果我的英语不正确。我会尽我的全力.. 问题是如何使用插入按钮从现有表中插入记录。除变量 $ book 外，一切正常。它将值0记录到数据库。这是代码..

//if the user press "INSERT BOOK" button there will be new record in database
<?php

$reader=$_SESSION['user_id'];
$book=$row['book_id'];

if (isset($_POST['update'])){
    $sql = "INSERT INTO `read` (`read_id`, `book`, `reader`) VALUES (LAST_INSERT_ID(), '$book' '$reader')";
    $result = mysql_query($sql) or die(mysql_error());

    if ($result) {
        echo " Yes, it works!";
    }
    else{
        echo "noup!";
    }
}

if(isset($_POST['submit'])){ 
    if(isset($_GET['go'])){ 
        if(preg_match("/^[  a-zA-Z]+/", $_POST['name'])){ 
            $name=$_POST['name'];

            $result = mysql_query("SELECT * FROM book b JOIN `read` r ON (b.book_id = r.book) JOIN users u ON (r.reader = u.user_id)    WHERE b.book_name LIKE '%" . $name .  "%' or b.writer LIKE '%" . $name .  "%' AND u.user_id !=". $_SESSION['user_id']);

            $num_rows = mysql_num_rows($result);
            if($num_rows>=1){
                echo "<table id='table1'>
                          <tr>
                              <th>book_id</th>
                              <th>BOOKNAME</th>
                              <th>WRITER</th>
                              <th>PAGES</th>
                          </tr>";

                while($row=mysql_fetch_array($result)){

                echo "<form action=add_book.php method='post'>";
                echo "<tr>";
                echo "<td>" . $row['book_id'] . "</td>";
                echo "<td>" . $row['book_name'] . "</td>";
                echo "<td>" . $row['writer'] . "</td>";
                echo "<td>" . $row['pages'] . "</td>";

              //echo "<td>" . "<input type = 'hidden' name = 'hidden' value ="  . $row['book_id'] . " </td>";
                echo "<td>" . "<input class = 'field' type = 'submit' name = 'update' value = 'INSERT BOOK'>" . " </td>";
                echo "</tr>";
                echo "</form>";
                }//WHILE LOOP
            echo  "</table>";
            }
            else{
                echo "NO RESULTS";
            }//else
        }//if(preg_match..)
    } //if(isset($_GET['go'])){ 
} //if(isset($_POST['submit'])){
?>