php - MySQL 显示结果

Question

请帮帮我。这里的任何人都可以告诉我为什么我的数据库的结果显示这样的链接吗？

 Art
 Art
 Art
 Art
 Music
 Music
 Music
 Music
 Drama
 Drama
 Drama
 Drama
 Medical
 Medical
 Medical

我想要这样显示类别，

Art
Music
Drama
Medical

...这是我在 index.php

中的代码

<?php 

             $dbh=mysql_connect("127.0.0.1","root","root") or die ('Cannot connedt to the Database' .mysql_errno()); 
             mysql_select_db("books");


             $res = "SELECT * FROM table1 ORDER BY category ASC";
             $res_query = mysql_query($res) or die (mysql_error());
             $ra = mysql_fetch_assoc($res_query);  

?>



     <?php do { ?>
       <p><a href="page.php?id=<?php echo $ra['id']; ?>"><?php echo $ra['category']; ?></a></p>
    <?php } while ($ra = mysql_fetch_assoc($res_query))?>

...这是我在 page.php 中显示结果的代码...

<?php 

$dbh=mysql_connect("127.0.0.1","root","root") or die ('Cannot connedt to the Database' .mysql_errno()); 
mysql_select_db("books");

if(isset($_GET['id'])){
$id = $_GET['id'];
}else {
$id=1;
}
$res = "SELECT * FROM table1 WHERE id=$id";
$res_query = mysql_query($res) or die (mysql_error());
$ra = mysql_fetch_assoc($res_query);  

?>


<h1><?php echo $ra['category']; ?></h1>
<p><?php echo $ra['author']; ?></p>
<p><?php echo $ra['title']; ?></p>

下面是我为我的藏书创建的数据库。

---

编号 |类别 |作者 |标题

1       |Art        |   Author1  |      title1
2       |Art        |   Author2  |  title2
3       |Art        |   Author3  |  title3
4       |Art        |       Author4  |  title4
5       |Music          |   Author1  |  title1
6       |Music          |   Author2  |  title2
7       |Music          |   Author3  |  title3
8       |Music          |   Author4  |  title4
9       |Drama          |   Author1  |  title1
10      |Drama          |   Author2  |  title2
11      |Drama          |   Author3  |  title3
12      |Drama          |   Author4  |  title4
13      |Medical    |   Author1  |  title1
14      |Medical    |   Author2  |  title2
15      |Medical    |   Author3  |  title3

---

Answer 1

试试这个，

修改 index.php 中的下面一行

$res = "SELECT * FROM table1 ORDER BY category ASC";

到

$res = "SELECT * FROM table1 GROUP BY category ORDER BY category ASC";