Head First PHP&MySQL学习笔记(六)
来源：互联网 发布：赵公明 知乎 编辑：程序博客网 时间：2024/04/28 03:15
九. 串与定制函数
1. 利用like,%增加搜索的灵活性；LIMIT控制一个SQL查询返回多少行以及哪些行
2. PHP explode()函数将一个串分解为一个子串数组；PHP implode()函数由子串构造一个串；
PHP str_replace()函数可以实现“查找-替换功能”；PHP substr()函数允许抽取一个串的一部分；
3. 通过预处理数据，可以删除我们不想要的字符，使数据更易于处理
4. 利用定制函数，可以按名组织一个PHP代码块，以便轻松地重用
5. 跟踪分页数据的常用变量：
$cur_page：用过$_GET从脚本URL得到当前页$cur_pages。如果未通过URL传递当前页，$cur_page则设置为第1页（1）；
$results_per_page：这是每一页上的显示结果数，可以根据页面的外观来选择，另外要考虑页面采用这种布局时放多少个搜索结果才合适。LIMIT字句的第二个参数就由这个变量确定；
$skip：计算开始当前页面上的行为之前要跳过的行数$skip。这个变量会控制每一页的结果从哪里开始，并为LIMIT字句提供第一个参数；
$total：运行一个不带LIMIT获取所有行的查询，然后统计结果数并存储在$total中
$num_pages：用$total除以$results_per_page计算页数$num_pages；
所以对于给定的搜索，总共有$total个匹配行，不过一次显示一页，每页包含$results_per_page个匹配行。共有$num_pages页，当前页由$cur_page标识
6. 代码示例：
<!-- connectvars.php --><?php // Define database connection constants define('DB_HOST', 'localhost'); define('DB_USER', 'root'); define('DB_PASSWORD', ''); define('DB_NAME', 'riskyjobs');?><!-- search.php --><!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" xml:lang="en" lang="en"><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Risky Jobs - Search</title> <link rel="stylesheet" type="text/css" href="style.css" /></head><body> <img src="riskyjobs_title.gif" alt="Risky Jobs" /> <img src="riskyjobs_fireman.jpg" alt="Risky Jobs" style="float:right" /> <h3>Risky Jobs - Search Results</h3><?php // This function builds a search query from the search keywords and sort setting function build_query($user_search, $sort) { $search_query = "SELECT * FROM riskyjobs"; // Extract the search keywords into an array $clean_search = str_replace(',', ' ', $user_search); $search_words = explode(' ', $clean_search); $final_search_words = array(); if (count($search_words) > 0) { foreach ($search_words as $word) { if (!empty($word)) { $final_search_words[] = $word; } } } // Generate a WHERE clause using all of the search keywords $where_list = array(); if (count($final_search_words) > 0) { foreach($final_search_words as $word) { $where_list[] = "description LIKE '%$word%'"; } } $where_clause = implode(' OR ', $where_list); // Add the keyword WHERE clause to the search query if (!empty($where_clause)) { $search_query .= " WHERE $where_clause"; } // Sort the search query using the sort setting switch ($sort) { // Ascending by job title case 1: $search_query .= " ORDER BY title"; break; // Descending by job title case 2: $search_query .= " ORDER BY title DESC"; break; // Ascending by state case 3: $search_query .= " ORDER BY state"; break; // Descending by state case 4: $search_query .= " ORDER BY state DESC"; break; // Ascending by date posted (oldest first) case 5: $search_query .= " ORDER BY date_posted"; break; // Descending by date posted (newest first) case 6: $search_query .= " ORDER BY date_posted DESC"; break; default: // No sort setting provided, so don't sort the query } return $search_query; } // This function builds heading links based on the specified sort setting function generate_sort_links($user_search, $sort) { $sort_links = ''; switch ($sort) { case 1: $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=2">Job Title</a></td><td>Description</td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=3">State</a></td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=5">Date Posted</a></td>'; break; case 3: $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=1">Job Title</a></td><td>Description</td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=4">State</a></td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=3">Date Posted</a></td>'; break; case 5: $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=1">Job Title</a></td><td>Description</td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=3">State</a></td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=6">Date Posted</a></td>'; break; default: $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=1">Job Title</a></td><td>Description</td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=3">State</a></td>'; $sort_links .= '<td><a href = "' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=5">Date Posted</a></td>'; } return $sort_links; } // This function builds navigational page links based on the current page and the number of pages function generate_page_links($user_search, $sort, $cur_page, $num_pages) { $page_links = ''; // If this page is not the first page, generate the "previous" link if ($cur_page > 1) { $page_links .= '<a href="' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=' . $sort . '&page=' . ($cur_page - 1) . '"><-</a> '; } else { $page_links .= '<- '; } // Loop through the pages generating the page number links for ($i = 1; $i <= $num_pages; $i++) { if ($cur_page == $i) { $page_links .= ' ' . $i; } else { $page_links .= ' <a href="' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=' . $sort . '&page=' . $i . '"> ' . $i . '</a>'; } } // If this page is not the last page, generate the "next" link if ($cur_page < $num_pages) { $page_links .= ' <a href="' . $_SERVER['PHP_SELF'] . '?usersearch=' . $user_search . '&sort=' . $sort . '&page=' . ($cur_page + 1) . '">-></a>'; } else { $page_links .= ' ->'; } return $page_links; } // Grab the sort setting and search keywords from the URL using GET $sort = $_GET['sort']; $user_search = $_GET['usersearch']; // Calculate pagination information $cur_page = isset($_GET['page']) ? $_GET['page'] : 1; $results_per_page = 5; // number of results per page $skip = (($cur_page - 1) * $results_per_page); // Start generating the table of results echo '<table border="0" cellpadding="2">'; // Generate the search result headings echo '<tr class="heading">'; echo generate_sort_links($user_search, $sort); echo '</tr>'; // Connect to the database require_once('connectvars.php'); $dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME); // Query to get the total results $query = build_query($user_search, $sort); $result = mysqli_query($dbc, $query); $total = mysqli_num_rows($result); $num_pages = ceil($total / $results_per_page); // Query again to get just the subset of results $query = $query . " LIMIT $skip, $results_per_page"; $result = mysqli_query($dbc, $query); while ($row = mysqli_fetch_array($result)) { echo '<tr class="results">'; echo '<td valign="top" width="20%">' . $row['title'] . '</td>'; echo '<td valign="top" width="50%">' . substr($row['description'], 0, 100) . '...</td>'; echo '<td valign="top" width="10%">' . $row['state'] . '</td>'; echo '<td valign="top" width="20%">' . substr($row['date_posted'], 0, 10) . '</td>'; echo '</tr>'; } echo '</table>'; // Generate navigational page links if we have more than one page if ($num_pages > 1) { echo generate_page_links($user_search, $sort, $cur_page, $num_pages); } mysqli_close($dbc);?></body></html>/* style.css */tr.heading { color: #882E2C;}tr.results { font-size: smaller; color: #000000;}a { text-decoration: none; font-weight: bold;}a:link { color: #882E2C;}a:hover { background-color: #E2F345;}a:visited { color: #882E2C;}a:active { color: #000000;}十. 正则表达式
1. 正则表达式是一些规则，用于匹配一个或多个串中的模式
2. 利用元字符可以在正则表达式中描述文本模式：
\d：匹配一位数字
\w：查找任何字母数字字符
\s：查找空白符（制表符，换行，回车符）
^：查找一个串的开始位置
.：点元字符可以匹配除了换行符以外的任意一个字符
[] 中的 \：‘或者’
\ … ?：…表示可选的内容
$：查找串尾
量词指定了一个元字符应当出现多少次；字符类是一组匹配单个字符的规则
3. 使用preg_match()检查模式：
例：preg_match(‘/^\d{3}-\d{2}-\d{4}$’,‘555-02-9983’)；
使用preg_replace()函数可以取代串中的匹配文本：
例：$new_year=preg_replace(‘/200[0-9]’,‘2015’,‘Thisyear is 2014.’)；
4. 通过标准化数据，可以得到更好的SQL查询结果
5. 验证通常是允许接受与实际接受之间的一个权衡
6. PHP checkdnsrr()函数检查一个域是否合法
7. 代码示例：<!-- registration.php --><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>Risky Jobs - Registration</title> <link rel="stylesheet" type="text/css" href="style.css" /></head><body> <img src="riskyjobs_title.gif" alt="Risky Jobs" /> <img src="riskyjobs_fireman.jpg" alt="Risky Jobs" style="float:right" /> <h3>Risky Jobs - Registration</h3><?php if (isset($_POST['submit'])) { $first_name = $_POST['firstname']; $last_name = $_POST['lastname']; $email = $_POST['email']; $phone = $_POST['phone']; $job = $_POST['job']; $resume = $_POST['resume']; $output_form = 'no'; if (empty($first_name)) { // $first_name is blank echo '<p class="error">You forgot to enter your first name.</p>'; $output_form = 'yes'; } if (empty($last_name)) { // $last_name is blank echo '<p class="error">You forgot to enter your last name.</p>'; $output_form = 'yes'; } if (!preg_match('/^[a-zA-Z0-9][a-zA-Z0-9\._\-&!?=#]*@/', $email)) { // $email is invalid because LocalName is bad echo '<p class="error">Your email address is invalid.</p>'; $output_form = 'yes'; } else { // Strip out everything but the domain from the email $domain = preg_replace('/^[a-zA-Z0-9][a-zA-Z0-9\._\-&!?=#]*@/', '', $email); // Now check if $domain is registered if (!checkdnsrr($domain)) { echo '<p class="error">Your email address is invalid.</p>'; $output_form = 'yes'; } } if (!preg_match('/^\(?[2-9]\d{2}\)?[-\s]\d{3}-\d{4}$/', $phone)) { // $phone is not valid echo '<p class="error">Your phone number is invalid.</p>'; $output_form = 'yes'; } if (empty($job)) { // $job is blank echo '<p class="error">You forgot to enter your desired job.</p>'; $output_form = 'yes'; } if (empty($resume)) { // $resume is blank echo '<p class="error">You forgot to enter your resume.</p>'; $output_form = 'yes'; } } else { $output_form = 'yes'; } if ($output_form == 'yes') {?><form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>"> <p>Register with Risky Jobs, and post your resume.</p> <table> <tr> <td><label for="firstname">First Name:</label></td> <td><input id="firstname" name="firstname" type="text" value="<?php echo $first_name; ?>"/></td></tr> <tr> <td><label for="lastname">Last Name:</label></td> <td><input id="lastname" name="lastname" type="text" value="<?php echo $last_name; ?>"/></td></tr> <tr> <td><label for="email">Email:</label></td> <td><input id="email" name="email" type="text" value="<?php echo $email; ?>"/></td></tr> <tr> <td><label for="phone">Phone:</label></td> <td><input id="phone" name="phone" type="text" value="<?php echo $phone; ?>"/></td></tr> <tr> <td><label for="job">Desired Job:</label></td> <td><input id="job" name="job" type="text" value="<?php echo $job; ?>"/></td> </tr> </table> <p> <label for="resume">Paste your resume here:</label><br /> <textarea id="resume" name="resume" rows="4" cols="40"><?php echo $resume; ?></textarea><br /> <input type="submit" name="submit" value="Submit" /> </p></form><?php } else if ($output_form == 'no') { echo '<p>' . $first_name . ' ' . $last_name . ', thanks for registering with Risky Jobs!<br />'; $pattern = '/[\(\)\-\s]/'; $replacement = ''; $new_phone = preg_replace($pattern, $replacement, $phone); echo 'Your phone number has been registered as ' . $new_phone . '.</p>'; // code to insert data into the RiskyJobs database... }?></body></html>/* style.css */.error { font-weight: bold; color: #FF0000;} 0 0
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