Question

我想减去数据库中的值，只是尝试任何方法，但它仍然失败。我不知道下面查询中的代码是否有效。请流利地向我解释，因为我很难理解代码的逻辑。我真的很感激，我会尽力做到最好谢谢你！

borrow.php

    <form method="post" action="borrow_save.php">

截止日期借

            <div class="span8">
                    <div class="alert alert-success"><strong>Select Book</strong></div>
                        <table cellpadding="0" cellspacing="0" border="0" class="table" id="example">

                            <thead>
                                <tr>

                                    <th>Acc No.</th>                                 
                                    <th>Book title</th>                                 
                                    <th>Category</th>
                                    <th>Author</th>
                                    <th>Publisher name</th>
                                    <th>status</th>
                                    <th>Add</th>

                                </tr>
                            </thead>
                            <tbody>

                              <?php  $user_query=mysqli_query($dbcon,"select * from book where status != 'Archive' ")or die(mysqli_error());
                                while($row=mysqli_fetch_array($user_query)){
                                $id=$row['book_id'];  

                                $copy=$row['book_copies'];


                                $cn=count($id);
                                for($i=0; $i < $cn; $i++)

                                        if($copy > 0){ ?>
                                            <tr class="del<?php echo $id ?>">


                                <td><?php echo $row['book_id']; ?></td>
                                <td><?php echo $row['book_title']; ?></td>
                                <td><?php echo $row ['catalog']; ?> </td> 
                                <td><?php echo $row['author']; ?> </td> 
                                 <td><?php echo $row['publisher_name']; ?></td>
                                  <td width=""><?php echo $row['status']; ?></td> 
                                <?php include('toolttip_edit_delete.php'); ?>
                                <td width="20">
                                            <input id="" class="uniform_on" name="selector[]" type="checkbox" value="<?php echo $id; ?>">

                                </td>

                                </tr>
                                <?php   }
                                ?>

                                <?php  }  ?>
                            </tbody>
                        </table>

            </form>

<script>        



$(".uniform_on").change(function(){
var max= 3;
if( $(".uniform_on:checked").length == max ){

    $(".uniform_on").attr('disabled', 'disabled');
             alert('3 Books are allowed per borrow');
    $(".uniform_on:checked").removeAttr('disabled');

}else{

     $(".uniform_on").removeAttr('disabled');
}
});

borrow_save.php

<?php


    $id=$_POST['selector'];
$member_id  = $_POST['member_id'];
$due_date  = $_POST['due_date'];

if ($id == '' ){ 
header("location: borrow.php");

}else{




mysqli_query($dbcon,"insert into borrow (member_id,date_borrow,due_date) values ('$member_id',NOW(),'$due_date')")or die(mysqli_error($dbcon));
$borrow_id = $row['borrow_id'];
$borrow_id=$dbcon->insert_id; 
mysqli_query($dbcon,"UPDATE book SET book_copies = book_copies - 1 where book_id='$book_id'");  <!- this is the query that I don't know if it's work -->


$N = count($id);

for($i=0; $i < $N; $i++)
{


mysqli_query($dbcon,"insert borrowdetails (book_id,borrow_id,borrow_status) values('$id[$i]','$borrow_id','pending')")or die(mysqli_error($dbcon));
}

}  
?>

Answer 1

您已经在val循环中以borrowdetails为基础插入book_id，因此最简单的解决方案是将该更新语句移动到该循环：

for

如何使用数据库中的复选框减去该值

1 个答案: