无法让我的脚本正确运行，我有 2 个 undefined index 错误和一个提供了无效参数的错误，我一生都无法弄清楚为什么会出现这种情况。 2 个 undefined index 错误来自这些行。
if(!is_null($_GET['order']) && $_GET['order'] != 'courseTitle')
和
if (!is_null($_GET['page']))
我的无效参数错误是这样的
Warning: Invalid argument supplied for foreach() in
由此生成
<?php foreach ($books as $book) : ?>
我在两个类之间的完整代码是这样的..我做错了什么有什么想法吗？为此我抓狂了。
index.php
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Catalog</title>
</head>
<body bgcolor="white">
<?php
/////////////////////////////////////////////////
//connect to db
/////////////////////////////////////////////////
$dsn = 'mysql:host=localhost;dbname=book_catalog';
$username = "php";
$password = "php";
$db = new PDO($dsn, $username, $password);
//get data
if(!is_null($_GET['order']) && $_GET['order'] != 'courseTitle')
{
$thesort = $_GET['order'];
$query = "Select * FROM book
INNER JOIN course
ON book.course = course.courseID
ORDER BY ".$_GET['order'];
}
else
{
$thesort = "courseTitle";
$query = "Select * FROM book
INNER JOIN course
ON book.course = course.courseID
ORDER BY $thesort";
}
//if page is null go to first page otherwise query for correct page
if (!is_null($_GET['page']))
{
$query = $query." LIMIT ".($_GET['page']*8-8).", 8";
}
else
{
$query = $query." LIMIT 0, 8";
}
//query result
$books = $db->query($query);
//get number of overall rows
$query2 = $db->query("SELECT * FROM book");
$count = $db->query("SELECT Count(*) As 'totalRecords' FROM book");
$count = $count->fetch();
$count = $count['totalRecords'];
?>
<table border =" 1">
<tr>
<th bgcolor="#6495ed"><a href="?order=course">Course #</th>
<th bgcolor="#6495ed"><a href="?order=courseTitle">Course Title</th>
<th bgcolor="#6495ed"><a href="?order=bookTitle">Book Title</th>
<th bgcolor="#6495ed"></th>
<th bgcolor="#6495ed"><a href="?order=price">Price</th>
</tr>
<?php foreach ($books as $book) : ?>
<tr>
<td><a href="rsc/catalog.pdf"><?php echo $book['course']; ?></a></td>
<td><?php echo $book['courseTitle']; ?></td>
<td><?php echo $book['bookTitle']; ?></td>
<td><?php
$bookcourse = $book['course'];
$isbn = $book['isbn13'];
$booklink = "<a href=\"course.php?course=$bookcourse&isbn=$isbn\">";
echo $booklink ;?><img src='images/<?php echo $book['isbn13'].'.jpg'; ?>'></a></td>
<td><?php echo $book['price']; ?></td>
</tr>
<?php endforeach; ?>
</tr>
</table>
<?php
//paging function... not sure if it works correctly?
for ($j=1; $j <= ceil($count/8); $j++)
{ ?>
<a href=<?php echo "?page=".$j."&order=".$thesort; ?>><?php echo $j; ?></a>
<?php
}?>
</body>
</html>
**course.php**
<?php
//get data from index.php
$course = $_GET['course'];
$isbn = $_GET['isbn'];
//connect to db
$dsn = 'mysql:host=localhost;dbname=book_catalog';
$username = "php";
$password = "php";
$db = new PDO($dsn, $username, $password);
//get data
$query = "Select * FROM book, course, author, publisher
WHERE book.isbn13 = $isbn AND book.course = '$course' AND book.course = course.courseID AND book.bookID = author.bookID AND book.publisher = publisher.publisherID
ORDER BY book.bookID";
//query results
$books = $db->query($query);
//error troubleshooting
if (!$books) {
echo "Could not successfully run query ($query) from DB: " . mysql_error();
exit;
}
//count the number of rows in the result
$results = $books->fetchAll();
$rowCount = count($book);
//get data from results
foreach($results as $book){
$bookID = $book['bookID'];
$bookTitle = $book['bookTitle'];
$isbn = $book['isbn13'];
$price = $book['price'];
$desc = $book['description'];
$publisher = $book['publisher'];
$courseTitle = $book['courseTitle'];
$courseID = $book['courseID'];
$credits = $book['credit'];
$edition = $book['edition'];
$publishDate = $book['publishDate'];
$length = $book['length'];
$firstName = $book['firstName'];
$lastName = $book['lastName'];
}
if($numrows > 1)
{
foreach ($books as $book)
{
$authorArray[] = $book['firstName'] + ' ' + $book['lastName'];
}
}
?>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>CIS Department Book Catalog</title>
</head>
<body bgcolor=white">
<table border="0">
<tr>
<td>
<img src='images/<?php echo $isbn.'.jpg'; ?>'>
</td>
<td>
<?php
echo "For Course: $courseID $courseTitle ($credits)";
echo "</br>";
echo "Book Title: $bookTitle";
echo "</br>";
echo "Price: $price";
echo "</br>";
echo "Author";
if ($numResults > 1)
{
echo "s:";
for ($i = 0; $i < $numResults; $i++)
{
if ($i!=0)
echo ", $authorArray[i]";
else
echo $authorArrat[i];
}
}
else
echo ": $firstName, $lastName";
echo "</br>";
echo "Publisher: $publisher";
echo "</br>";
echo "Edition: $edition ($publishDate)";
echo "</br>";
echo "Length: $length pages";
echo "</br>";
echo "ISBN-13: $isbn";
?>
</td>
</tr>
<tr>
<td colspan="2">
<?php echo "Description: $desc"; ?>
</td>
</tr>
</table>
</body>
</html>
最佳答案
您应该使用
isset而不是is_null来防止它发出有关 undefined variable 的警告。$books从未定义foreach需要它是一个数组。无论如何，您确实不需要它，使用while循环将每一行获取到数组中。 (请参阅下面我的示例)。您还在查询中多次重新定义$count。
就像@Brad 所说。使用准备好的语句和占位符。您的数据库最终将被您当前的代码入侵。
编辑
回答你的问题。 query() 返回一个语句句柄。 (我将其定义为 $sth)。 fetch() 返回一个结果，您需要传递一个获取模式常量(或者使用 $db->setFetchMode())
获取您需要的书籍
$books = array();
$sth = $db->query($query);
while( $row = $sth->fetch(PDO::FETCH_ASSOC) ) {
$books[] = $row; // appends each row to the array
}
以下是您的代码应该如何获取计数。
// you're not using the $query2 you defined ... just remove it
$sth = $db->query("SELECT Count(*) As 'totalRecords' FROM book");
$result = $sth->fetch(PDO::FETCH_ASSOC);
$count = $result['totalRecords'];
看一下: http://wiki.hashphp.org/PDO_Tutorial_for_MySQL_Developers看起来是一个很好的指南，可以让您深入了解如何使用 PDO。特别注意错误处理和准备好的语句!
关于PHP MySQL 未定义索引等错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16312153/