Question

我正在使用php和mysql的更新文件，但更新功能不起作用。我使用示例编写代码并根据要求进行修改。该文件确实有效，并没有真正删除任何错误，但它不会更改数据库中的任何内容。假设更新图书数据库。

代码：

<?php 

$page_title = 'Add Books';
include ('bookincludes/header.html');

// Check for form submission:
if ($_SERVER['REQUEST_METHOD'] == 'POST') {

    require ('../mysqli_connect.php'); // Connect to the db.

    $errors = array(); // Initialize an error array.

    if (empty($_POST['title'])) {
        $errors[] = 'Please add title.';
    } else {
        $e = mysqli_real_escape_string($dbc, trim($_POST['title']));
    }

    if (empty($_POST['author'])) {
        $errors[] = 'Please add the name of the author.';
    } else {
        $p = mysqli_real_escape_string($dbc, trim($_POST['author']));
    }


    if (!empty($_POST['isbn1'])) {
        if ($_POST['isbn1'] != $_POST['isbn2']) {
            $errors[] = 'ISBN number does not match.';
        } else {
            $np = mysqli_real_escape_string($dbc, trim($_POST['isbn1']));
        }
    } else {
        $errors[] = 'You need to enter ISBN number.';
    }

    if (empty($errors)) { // If everything's OK.

        $q = "SELECT ISBN FROM Books WHERE (Title='$e' AND Author ='$p')";
        $r = @mysqli_query($dbc, $q);
        $num = @mysqli_num_rows($r);
        if ($num == 1) { // Match was made.

            $row = mysqli_fetch_array($r, MYSQLI_NUM);

            // Make the UPDATE query:
            $q = "UPDATE Books SET ISBN='$np' WHERE ISBN = $row[0] ";       
            $r = mysqli_query($dbc, $q);

            if (mysqli_affected_rows($dbc) == 1) { // If it ran OK.

                // Print a message.
                echo '<h1>Thank you!</h1>
                <p>Thank you, Book has been added or modified</p><p><br /></p>';    

            } else { // If it did not run OK.

                // Public message:
                echo '<h1>System Error</h1>
                <p class="error">System error. We apologize for any inconvenience.</p>'; 

                // Debugging message:
                echo '<p>' . mysqli_error($dbc) . '<br /><br />Query: ' . $q . '</p>';

            }

            mysqli_close($dbc); // Close the database connection.

            // Include the footer and quit the script (to not show the form).
            include ('includes/footer.html'); 
            exit();

        } else {
            echo '<h1>Error!</h1>
            <p class="error">ISBN number is incorrect.</p>';
        }

    } else { // Report the errors.

        echo '<h1>Error!</h1>
        <p class="error">The following error(s) occurred:<br />';
        foreach ($errors as $msg) { // Print each error.
            echo " - $msg<br />\n";
        }
        echo '</p><p>Please try again.</p><p><br /></p>';

    } // End of if (empty($errors)) IF.

    mysqli_close($dbc); // Close the database connection.

} // End of the main Submit conditional.
?>
<h1>Update</h1>
<form action="Bupdate.php" method="post">
    <p>ISBN number: <input type="text" name="isbn1" size="20" maxlength="60" value="<?php if (isset($_POST['isbn1'])) echo $_POST['isbn1']; ?>"  /> </p>
    <p>Confirm ISBN: <input type="text" name="isbn2" size="20" maxlength="60" value="<?php if (isset($_POST['isbn2'])) echo $_POST['isbn2']; ?>"  /> </p>
    <p>Author: <input type="text" name="author" size="20" maxlength="60" value="<?php if (isset($_POST['author'])) echo $_POST['author']; ?>"  /></p>
    <p>Title: <input type="text"" name="title" size="20" maxlength="60" value="<?php if (isset($_POST['title'])) echo $_POST['title']; ?>"  /></p>
    <p>Year: <input type="text"" name="year" size="20" maxlength="60" value="<?php if (isset($_POST['year'])) echo $_POST['year']; ?>"  /></p>
    <p><input type="submit" name="submit" value="Update" /></p>
</form>
<?php include ('bookincludes/footer.html'); ?>

如果我尝试更改ISBN，这就是：

系统错误。对由此带来的任何不便，我们深表歉意。

查询：更新书籍SET ISBN ='978-1782175910'WHERE ISBN =   978-1782175919

如果我尝试更新ISBN或年份，但我收到上述消息。我该如何解决这个问题？

Answer 1

查询要求文本值包含在这样的引号中

$q = "UPDATE Books SET ISBN='$np' WHERE ISBN = '$row[0]'";

虽然我会寻找一个使用参数化和准备好的查询而不是字符串连接查询来避免SQL注入的教程

任何建议使用@错误沉默前缀的教程都应该告诉你作者不知道他们在做什么，应该像瘟疫一样避免。

Answer 2

你似乎缺少where子句

上的单引号

 UPDATE Books SET ISBN='978-1782175910' WHERE ISBN = 978-1782175919

应该是

 UPDATE Books SET ISBN='978-1782175910' WHERE ISBN = '978-1782175919'

更新功能php

2 个答案: