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Question

我正在开发自定义CMS。我的问题是我有一个帖子有两个类别'教程'和'语言'。我想将其显示为类别页面中的项目。

这是我的book_category表

这是我的书桌。

问题1：如何在多个类别的数据库中存储图书？我应该将类别ID作为字符串值存储在数据库中吗？

问题2：如何查询多个类别的帖子？

这是我的header.php代码

<?php  include 'includes/db.php'; ?>
<html lang="fa-IR" dir="rtl">
   <head>
      <title>CMS کتابخانه</title>
      <script type="text/javascript" src="./assets/js/jquery.min.js"></script>
      <script type="text/javascript" src="./assets/js/bootstrap.js"></script>
      <link rel="stylesheet" href="./assets/css/bootstrap.min.css" type="text/css" >
      <link rel="stylesheet" href="./assets/css/bootstrap.rtl.min.css" type="text/css" >
      <link rel="stylesheet" href="./assets/css/main.css" type="text/css" >
      <link href="./assets/css/fontawesome-all.min.css" rel="stylesheet">
   </head>
   <body>
      <nav class="navbar navbar-expand-lg navbar-dark bg-dark">
        <a class="navbar-brand" id="logo" href="#">کتابخانه من</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
          <span class="navbar-toggler-icon"></span>
        </button>
        <div class="collapse navbar-collapse" id="navbarNav">
          <ul class="navbar-nav">
            <li class="nav-item <?php if($_SERVER['REQUEST_URI'] == '/cms/' || $_SERVER['REQUEST_URI'] == '/cms/index.php' ){echo 'active';} ?>">
              <a class="nav-link" href="index.php">خانه <span class="sr-only"></span></a>
            </li>
            <li class="nav-item dropdown">
              <a class="nav-link dropdown-toggle" href="#" id="navbardrop" data-toggle="dropdown">
               دسته بندی
              </a>
              <div class="dropdown-menu">
            <?php 
               $select_cat = mysqli_query($connection,"SELECT * FROM book_category");
                while($row = mysqli_fetch_array($select_cat)) {

                if(isset($_GET['category_name'])){
                  if($_GET['id'] == $row['category_id']){
                     $class='active';
                  }else{
                     $class='';
                  }
                }else{
                  $class='';
                }
                echo '<a class="dropdown-item '.$class.'" href="book_category.php?id='.$row['category_id'].'">'.$row['category_name'].'</a>';
                }
            ?>

              </div>
            </li>
            <li class="nav-item">
              <a class="nav-link" href="#">داغ ترین ها</a>
            </li>
            <li class="nav-item">
              <a class="nav-link" href="#">نویسندگان</a>
            </li>
            <?php if(!isset($_SESSION['user'])) : ?>
            <li class="nav-item">
              <a class="nav-link" href="register.php">عضویت</a>
            </li>
            <?php endif; ?>
          </ul>
        </div>
      </nav>
      <div class="p-2"></div>

这是我的category.php，用于显示特定类别的帖子。

<?php include 'includes/header.php'; ?>
      <div class="container">
         <nav class="navbar navbar-expand-lg navbar-dark bg-dark">
          <a class="navbar-brand" href="#">آخرین کتاب ها</a>
        </nav>
         <article class="row">
            <section class="col-lg-8">
            <div class="card-columns">
            <?php 
               $result = mysqli_query($connection,"SELECT * FROM books WHERE cat_id = ");
                while($row = mysqli_fetch_array($result)) :
            ?>
               <div class="card">
                 <img class="card-img-top rounded mx-auto d-block" src="<?php echo $row['image']; ?>" alt="<?php echo $row['title']; ?>" width="199" height="312">
                 <div class="card-body text-right">
                  <h3 class="card-title"><a href="post.php?id=<?php echo $row['id']; ?>"><?php echo $row['title']; ?></a></h3>
                  <p class="card-text"><?php echo mb_substr($row['description'],0,250); echo '...'; ?></p>
                   <a href="book.php?id=<?php echo $row['id']; ?>" class="btn btn-primary">ادامه مطلب</a>
                 </div>
               </div>
            <?php endwhile; ?>
            </div>
         </section>
         <?php include 'includes/sidebar.php'; ?>
         </article>
      </div>
      <div style="width:50px;height:50px;"></div>
<?php include 'includes/footer.php'; ?>
   </body>
</html>

Answer 1

You should search the internet for many to many relationships:

One book may have zero or more categories. On the other side one category may have zero or more book relations. This relation is called many to many.

To archive this goal you have to add an mapping table:

table: book   table: book_category   table: category
==========    ====================   ===============
- id          - book_id              - id
- name        - category_id          - name
- author                             - ...
- ...

To query the data there are examples here how to query many-to-many?. You should find many examples for php in the internet ...

Remark: OPs question switches between book and post entity. I decided to use book ... ;)

Edit 1:

OPs question in comment: how to add row for submitted book ...?

You have to know the relevant book and category ids. To connect a book to a catetory, you simply add the id's to the join table.

INSERT INTO book_category(book_id,category_id) values(40,50);

In this example the book with id 40 is joined to the category id 50.

If your question is targeting an php example, I can't tell you because I don't know how your DAO layer is implemented. But this should be a new question I guess.

Answer 2

If a book always has one category you can simply add a field category_id to your book's table, but when a book can have multiple categories and you don't know how much. You can do best by creating a second table that connects with multiple rows of multiple categories.

Create a table books_category with fields like id, books_id, books_category_id. Also make indexes on books_id, books_category_id for fast searching.

For your Query, you should use the INNER JOIN.

SELECT * FROM `books` INNER JOIN `books_category`  ON `books_category`.`books_id` =  `books`.`id` WHERE `books_category`.`books_category_id` = 5

如何在类别页面中获取多个类别帖子？

2 个答案:

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