封装自己的DB类（PHP），封装db类php
封装一个DB类，用来专门操作数据库，以后凡是对数据库的操作，都由DB类的对象来实现。这样有了自己的DB类，写项目时简单的sql语句就不用每次写了，直接调用就行，很方便！
1.封装一个DB类。一个类文件应该只有一个类，其他的内容全部都没有。类文件的命名规则：类名.class.php
下面是创建DB类的代码：
<?<span>php
</span><span>//</span><span>封装一个DB类，用来专门操作数据库，以后凡是对数据库的操作，都由DB类的对象来实现</span>
<span>class</span><span> DB{
</span><span>//</span><span>属性</span>
<span>private</span> <span>$host</span><span>;
</span><span>private</span> <span>$port</span><span>;
</span><span>private</span> <span>$user</span><span>;
</span><span>private</span> <span>$pass</span><span>;
</span><span>private</span> <span>$dbname</span><span>;
</span><span>private</span> <span>$charset</span><span>;
</span><span>private</span> <span>$prefix</span>; <span>//</span><span>表前缀</span>
<span>private</span> <span>$link</span>; <span>//</span><span>连接资源（连接数据库，一般会返回一个资源，所以需要定义一个link属性）
//构造方法(作用：为了初始化对象的属性)，会被自动调用</span>
<span>/*</span><span>
* @param1 array $arr，默认为空，里面是一个关联数组，里面有7个元素
* array('host' => 'localhost','port' => '3306');
</span><span>*/</span>
<span>public</span> <span>function</span> __construct(<span>$arr</span> = <span>array</span><span>()){
</span><span>//</span><span>初始化</span>
<span>$this</span>->host = <span>isset</span>(<span>$arr</span>['host']) ? <span>$arr</span>['host'] : 'localhost';<span>//</span><span>先判断是否有自己的host，如果有就用自己的host，否则就使用默认的localhost</span>
<span>$this</span>->port = <span>isset</span>(<span>$arr</span>['port']) ? <span>$arr</span>['port'] : '3306'<span>;
</span><span>$this</span>->user = <span>isset</span>(<span>$arr</span>['user']) ? <span>$arr</span>['user'] : 'root'<span>;
</span><span>$this</span>->pass = <span>isset</span>(<span>$arr</span>['pass']) ? <span>$arr</span>['pass'] : 'root'<span>;
</span><span>$this</span>->dbname = <span>isset</span>(<span>$arr</span>['dbname']) ? <span>$arr</span>['dbname'] : 'mydatabase'<span>;
</span><span>$this</span>->charset = <span>isset</span>(<span>$arr</span>['charset']) ? <span>$arr</span>['charset'] : 'utf8'<span>;
</span><span>$this</span>->prefix = <span>isset</span>(<span>$arr</span>['prefix']) ? <span>$arr</span>['prefix'] : ''<span>;
</span><span>//</span><span>连接数据库（类是要操作数据库，因此要连接数据库）</span>
<span>$this</span>-><span>connect();
</span><span>//</span><span>设置字符集</span>
<span>$this</span>-><span>setCharset();
</span><span>//</span><span>选择数据库</span>
<span>$this</span>-><span>setDbname();
}
</span><span>/*</span><span>
* 连接数据库
</span><span>*/</span>
<span>private</span> <span>function</span><span> connect(){
</span><span>//</span><span>mysql扩展连接</span>
<span>$this</span>->link = <span>mysql_connect</span>(<span>$this</span>->host . ':' . <span>$this</span>->port,<span>$this</span>->user,<span>$this</span>-><span>pass);
</span><span>//</span><span>判断结果</span>
<span>if</span>(!<span>$this</span>-><span>link){
</span><span>//</span><span>结果出错了
//暴力处理，如果是真实线上项目（生产环境）必须写入到日志文件</span>
<span>echo</span> '数据库连接错误：<br/>'<span>;
</span><span>echo</span> '错误编号' . <span>mysql_errno</span>() . '<br/>'<span>;
</span><span>echo</span> '错误内容' . <span>mysql_error</span>() . '<br/>'<span>;
</span><span>exit</span><span>;
}
}
</span><span>/*</span><span>
* 设置字符集
</span><span>*/</span>
<span>private</span> <span>function</span><span> setCharset(){
</span><span>//</span><span>设置</span>
<span>$this</span>->db_query("set names {<span>$this</span>->charset}"<span>);
}
</span><span>/*</span><span>
* 选择数据库
</span><span>*/</span>
<span>private</span> <span>function</span><span> setDbname(){
</span><span>$this</span>->db_query("use {<span>$this</span>->dbname}"<span>);
}
</span><span>/*</span><span>
* 增加数据
* @param1 string $sql，要执行的插入语句
* @return boolean，成功返回是自动增长的ID，失败返回FALSE
</span><span>*/</span>
<span>public</span> <span>function</span> db_insert(<span>$sql</span><span>){
</span><span>//</span><span>发送数据</span>
<span>$this</span>->db_query(<span>$sql</span><span>);
</span><span>//</span><span>成功返回自增ID</span>
<span>return</span> <span>mysql_affected_rows</span>() ? <span>mysql_insert_id</span>() : <span>FALSE</span><span>;
}
</span><span>/*</span><span>
* 删除数据
* @param1 string $sql，要执行的删除语句
* @return Boolean，成功返回受影响的行数，失败返回FALSE
</span><span>*/</span>
<span>public</span> <span>function</span> db_delete(<span>$sql</span><span>){
</span><span>//</span><span>发送SQL</span>
<span>$this</span>->db_query(<span>$sql</span><span>);
</span><span>//</span><span>判断结果</span>
<span>return</span> <span>mysql_affected_rows</span>() ? <span>mysql_affected_rows</span>() : <span>FALSE</span><span>;
}
</span><span>/*</span><span>
* 更新数据
* @param1 string $sql，要执行的更新语句
* @return Boolean，成功返回受影响的行数，失败返回FALSE
</span><span>*/</span>
<span>public</span> <span>function</span> db_update(<span>$sql</span><span>){
</span><span>//</span><span>发送SQL</span>
<span>$this</span>->db_query(<span>$sql</span><span>);
</span><span>//</span><span>判断结果</span>
<span>return</span> <span>mysql_affected_rows</span>() ? <span>mysql_affected_rows</span>() : <span>FALSE</span><span>;
}
</span><span>/*</span><span>
* 查询：查询一条记录
* @param1 string $sql，要查询的SQL语句
* @return mixed，成功返回一个数组，失败返回FALSE
</span><span>*/</span>
<span>public</span> <span>function</span> db_getRow(<span>$sql</span><span>){
</span><span>//</span><span>发送SQL</span>
<span>$res</span> = <span>$this</span>->db_query(<span>$sql</span><span>);
</span><span>//</span><span>判断返回</span>
<span>return</span> <span>mysql_num_rows</span>(<span>$res</span>) ? <span>mysql_fetch_assoc</span>(<span>$res</span>) : <span>FALSE</span><span>;
}
</span><span>/*</span><span>
* 查询：查询多条记录
* @param1 string $sql，要查询的SQL语句
* @return mixed，成功返回一个二维数组，失败返回FALSE
</span><span>*/</span>
<span>public</span> <span>function</span> db_getAll(<span>$sql</span><span>){
</span><span>//</span><span>发送SQL</span>
<span>$res</span> = <span>$this</span>->db_query(<span>$sql</span><span>);
</span><span>//</span><span>判断返回</span>
<span>if</span>(<span>mysql_num_rows</span>(<span>$res</span><span>)){
</span><span>//</span><span>循环遍历</span>
<span>$list</span> = <span>array</span><span>();
</span><span>//</span><span>遍历</span>
<span>while</span>(<span>$row</span> = <span>mysql_fetch_assoc</span>(<span>$res</span><span>)){
</span><span>$list</span>[] = <span>$row</span><span>;
}
</span><span>//</span><span>返回</span>
<span>return</span> <span>$list</span><span>;
}
</span><span>//</span><span>返回FALSE</span>
<span>return</span> <span>FALSE</span><span>;
}
</span><span>/*</span><span>
* mysql_query错误处理
* @param1 string $sql，需要执行的SQL语句
* @return mixed，只要语句不出错，全部返回
</span><span>*/</span>
<span>private</span> <span>function</span> db_query(<span>$sql</span><span>){
</span><span>//</span><span>发送SQL</span>
<span>$res</span> = <span>mysql_query</span>(<span>$sql</span><span>);
</span><span>//</span><span>判断结果</span>
<span>if</span>(!<span>$res</span><span>){
</span><span>//</span><span>结果出错了
//暴力处理，如果是真实线上项目（生产环境）必须写入到日志文件</span>
<span>echo</span> '语句出现错误：<br/>'<span>;
</span><span>echo</span> '错误编号' . <span>mysql_errno</span>() . '<br/>'<span>;
</span><span>echo</span> '错误内容' . <span>mysql_error</span>() . '<br/>'<span>;
</span><span>exit</span><span>;
}
</span><span>//</span><span>没有错误</span>
<span>return</span> <span>$res</span><span>;
}
</span><span>//</span><span>__sleep方法</span>
<span>public</span> <span>function</span><span> __sleep(){
</span><span>//</span><span>返回需要保存的属性的数组</span>
<span>return</span> <span>array</span>('host','port','user','pass','dbname','charset','prefix'<span>);
}
</span><span>//</span><span>__wakeup方法</span>
<span>public</span> <span>function</span><span> __wakeup(){
</span><span>//</span><span>连接资源</span>
<span>$this</span>-><span>connect();
</span><span>//</span><span>设置字符集和选中数据库</span>
<span>$this</span>-><span>setCharset();
</span><span>$this</span>-><span>setDbname();
}
</span><span>/*</span><span>
* 获取完整的表名
</span><span>*/</span>
<span>protected</span> <span>function</span><span> getTableName(){
</span><span>//</span><span>完整表名：前缀+表名</span>
<span>return</span> <span>$this</span>->prefix . <span>$this</span>-><span>table;
}
}
</span><span>//</span><span>这个DB类，一般不写析构（不释放资源） </span>
2.使用DB类，但是如果要使用某一个类来创建对象，必须要保证该类已经被加载到代码区里。可以使用一个魔术函数来实现对类的自动加载
自动加载：当一个脚本文件在执行某些语句的时候（实例化）需要去代码区里寻找对应的类，如果找不到会通过自动加载函数来将对应的类文件进行加载。
魔术函数：__autoload()
比如我们在index.php页面中需要使用DB类，那么我们就直接调用即可，具体代码如下：
<?<span>php
</span><span>//</span><span>使用DB类的对象来访问数据库
//先加载类文件
//include_once 'DB.class.php';
//如果想使用其他类，又需要加载（所以使用魔术函数__autoload来实现类的自动加载）
//显示的写出魔术函数__autoload
//参数：需要加载的类的名字</span>
<span>function</span> __autoload(<span>$a</span><span>){
</span><span>//</span><span>将对应的类文件加载进来</span>
<span>if</span>(<span>is_file</span>("<span>$a</span>.class.php"<span>)){
</span><span>include_once</span> "<span>$a</span>.class.php"<span>;
}
}
</span><span>//</span><span>实例化</span>
<span>$db</span> = <span>new</span> DB(<span>array</span>('dbname' => 'mydatabase'<span>));
</span>
陳述
本文內容由網友自願投稿，版權歸原作者所有。本站不承擔相應的法律責任。如發現涉嫌抄襲或侵權的內容，請聯絡admin@php.cn
熱AI工具
Undresser.AI Undress
人工智慧驅動的應用程序，用於創建逼真的裸體照片
AI Clothes Remover
用於從照片中去除衣服的線上人工智慧工具。
Undress AI Tool
免費脫衣圖片
Clothoff.io
AI脫衣器
Video Face Swap
使用我們完全免費的人工智慧換臉工具，輕鬆在任何影片中換臉！
熱門文章
刺客信條陰影：貝殼謎語解決方案
3 週前ByDDD
Windows 11 KB5054979中的新功能以及如何解決更新問題
2 週前ByDDD
在哪裡可以找到原子中的起重機控制鑰匙卡
3 週前ByDDD
<🎜>：死鐵路 - 如何完成所有挑戰
4 週前ByDDD
Atomfall指南：項目位置，任務指南和技巧
4 週前ByDDD
熱工具
禪工作室 13.0.1
強大的PHP整合開發環境
DVWA
Damn Vulnerable Web App (DVWA) 是一個PHP/MySQL的Web應用程序，非常容易受到攻擊。它的主要目標是成為安全專業人員在合法環境中測試自己的技能和工具的輔助工具，幫助Web開發人員更好地理解保護網路應用程式的過程，並幫助教師/學生在課堂環境中教授/學習Web應用程式安全性。 DVWA的目標是透過簡單直接的介面練習一些最常見的Web漏洞，難度各不相同。請注意，該軟體中
mPDF
mPDF是一個PHP庫，可以從UTF-8編碼的HTML產生PDF檔案。原作者Ian Back編寫mPDF以從他的網站上「即時」輸出PDF文件，並處理不同的語言。與原始腳本如HTML2FPDF相比，它的速度較慢，並且在使用Unicode字體時產生的檔案較大，但支援CSS樣式等，並進行了大量增強。支援幾乎所有語言，包括RTL（阿拉伯語和希伯來語）和CJK（中日韓）。支援嵌套的區塊級元素（如P、DIV），
SublimeText3 英文版
推薦：為Win版本，支援程式碼提示！
SublimeText3漢化版
中文版，非常好用
