我对php和数据库程序很陌生，但正在努力学习这门语言并为我的库开发一个系统。我有一个名为booksdb的数据库和两个名为"books"的表，其中包含图书和作者的标题，bookcatname包含具有唯一类别ID的图书类别。
我想做的是，在页面上显示所有类别，当一个类别链接被点击时，我想看到该特定类别下的书籍和作者的名字显示在另一个页面上，
的例子:
Art;
Color and Light by James Gurney
The Art Spirit by Robert Henry
How Pictures Work by David Bayles
Imaginative Realism by James Gurney
这是我的代码，但它不工作。
<?php
$dbh=mysql_connect("localhost","root","root") or die ('Cannot connedt to the Database' .mysql_errno());
mysql_select_db("booksdb");
//$res = "SELECT * FROM bookstable GROUP BY category ORDER BY category ASC";
$res = "SELECT * FROM bookcatname ORDER BY category ASC";
$res_query = mysql_query($res) or die (mysql_error());
$ra = mysql_fetch_assoc($res_query);
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Select a Company</title>
</head>
<body>
<?php do { ?>
<p><a href="page.php?cat_id=<?php echo $ra['cat_id']; ?>"><?php echo $ra['category']; ?></a></p>
<?php } while ($ra = mysql_fetch_assoc($res_query))?>
</body>
</html>
1.Table name - bookcatname
+----+--------+----------+
| id | cat_id | category |
+----+--------+----------+
| 1 | 1 | Art |
| 2 | 2 | Drama |
| 3 | 3 | Music |
| 4 | 4 | Fiction |
| 5 | 5 | Computer |
+----+--------+----------+
2.Table name - books
+----+--------+---------------------------------+-----------------------+
| id | cat_id | title | author |
+----+--------+---------------------------------+-----------------------+
| 1 | 1 | Color and Light | James Gurney |
| 2 | 1 | The Art Spirit | Robert Henry |
| 3 | 1 | Art & Fear | David Bayles |
| 4 | 1 | How Pictures Work | Molly Bang |
| 5 | 1 | Imaginative Realism | James Gurney |
| 6 | 2 | A Walk To Remember | Nicholas Sparks |
| 7 | 2 | An Old Fashioned Girl | Louisa May Alcott |
| 8 | 3 | The Rest Is Noise | Alex Ross |
| 9 | 3 | It Still Moves | Amanda Petrusich |
| 10 | 3 | Chronicles | Bob Dylan |
| 11 | 3 | Dream Boogie | Peter Guralnick |
| 12 | 3 | Escaping The Delta | Robert Johnson |
| 13 | 4 | Atlas Shrugged | Ayn Rand |
| 14 | 4 | Anthem | Ayn Rand |
| 15 | 4 | Sons and Lovers | D.H. Lawrence |
| 16 | 4 | Henderson the Rain King | Saul Bellow |
| 17 | 5 | The Art of Computer Programming | Donald Knuth |
| 18 | 5 | The Art of Unix Programming | Eric Raymond |
| 19 | 5 | Free Software, Free Society | Richard M. Stallman |
| 20 | 5 | Database System Concepts | Abraham Silberschatz |
| 21 | 5 | 3ds Max 2008 in Simple Steps | Kognet Solutions Inc. |
+----+--------+---------------------------------+-----------------------+
您当前显示类别的代码不工作，因为您使用:
$ra = mysql_fetch_assoc($res_query);
，然后在循环中再执行一次:
while ($ra = mysql_fetch_assoc($res_query)
只做一个while()来获取类别:
$getCategories = mysql_query("SELECT * FROM bookcatname ORDER BY category ASC");
while ($category = mysql_fetch_assoc($res_query) )
{
echo '<a href="page.php?cat_id='.$category['cat_id'].'">'.$category['category'].'</a>';
}
现在，您将需要另一个页面从该类别中获取书籍(或者您可以在同一页面中进行)。
books.php
// Same stuff here to connect database
// you check if a category is sent, else you redirect to categories page.
if ( empty($_GET['cat_id']) )
{
header('Location: index.php');
exit();
}
// Now you get books from category
// intval() convert to number
$getBooks = mysql_query("SELECT * FROM books WHERE cat_id = '".intval($_GET['cat_id'])."'");
echo '<ul>';
while ( $book = mysql_fetch_assoc($getBooks) )
{
echo '<li>'.$book['title'].' by '.$book['author'].'</li>';
}
echo '</ul>';