php 自己写的简单数据库类（pdo）

<span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;"></span><h1 style="margin: 0px 10px 10px 0px; padding: 0px; font-size: 28px; color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; background-color: rgb(242, 242, 242);">如何使用PDO连接数据库，操作数据库</h1><?php<br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$dbms=’mysql’;     //数据库类型 Oracle 用ODI,对于开发者来说，使用不同的数据库，只要改这个，不用记住那么多的函数了</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$host=’localhost’; //数据库主机名</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$dbName=’test’;    //使用的数据库</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$user=’root’;      //数据库连接用户名</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$pass=”;          //对应的密码</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$dsn=”$dbms:host=$host;dbname=$dbName”;</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">//</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">try {</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$dbh = new PDO($dsn, $user, $pass); //初始化一个PDO对象，就是创建了数据库连接对象$dbh</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">echo ”连接成功”;</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">/*你还可以进行一次搜索操作</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">foreach ($dbh->query(‘SELECT * from FOO’) as $row) {</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">print_r($row); //你可以用 echo($GLOBAL); 来看到这些值</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">}</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">*/</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$dbh = null;</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">} catch (PDOException $e) {</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">die (“Error!: ” . $e->getMessage() . ””);</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">}</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">//默认这个不是长连接，如果需要数据库长连接，需要最后加一个参数：array(PDO::ATTR_PERSISTENT => true) 变成这样：</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$db = new PDO($dsn, $user, $pass, array(PDO::ATTR_PERSISTENT => true));</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">?></span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">★数据库查询：</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">上面我们已经进行了一次查询，我们还可以使用如下的查询：</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;"><?php</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$db->setAttribute(PDO::ATTR_CASE, PDO::CASE_UPPER); //设置属性</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$rs = $db->query(“SELECT * FROM foo”);</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$rs->setFetchMode(PDO::FETCH_ASSOC);</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$result_arr = $rs->fetchAll();</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">print_r($result_arr);</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">?></span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">以上因为用到setAttribute()方法，放上那两个参数，把字段名强制转换成大写。下面列出多有PDO::setAttribute()的参数：</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::ATTR_CASE: 强制列名变成一种格式，详细如下(第二个参数)：</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::CASE_LOWER: 强制列名是小写.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::CASE_NATURAL: 列名按照原始的方式</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::CASE_UPPER: 强制列名为大写.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::ATTR_ERRMODE: 错误提示.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::ERRMODE_SILENT: 不显示错误信息，只显示错误码.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::ERRMODE_WARNING: 显示警告错误.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::ERRMODE_EXCEPTION: 抛出异常.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::ATTR_ORACLE_NULLS (不仅仅是ORACLE有效，别的数据库也有效): ）指定数据库返回的NULL值在php中对应的数值。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::NULL_NATURAL: 不变.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::NULL_EMPTY_STRING: Empty string is converted to NULL.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">o PDO::NULL_TO_STRING: NULL is converted to an empty string.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::ATTR_STRINGIFY_FETCHES: Convert numeric values to strings when fetching. Requires bool.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::ATTR_STATEMENT_CLASS: Set user-supplied statement class derived from PDOStatement. Cannot be used with persistent PDO instances. Requires array(string classname, array(mixed constructor_args)).</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::ATTR_AUTOCOMMIT (available in OCI, Firebird and MySQL): Whether to autocommit every single statement.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• PDO::MYSQL_ATTR_USE_BUFFERED_QUERY (available in MySQL): Use buffered queries.</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">例子中的$rs->setFetchMode(PDO::FETCH_ASSOC);是PDOStatement::setFetchMode()，对返回类型的声明。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">有如下：</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::FETCH_ASSOC – 关联数组形式</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::FETCH_NUM   – 数字索引数组形式</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::FETCH_BOTH  – 两者数组形式都有，这是缺省的</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::FETCH_OBJ   – 按照对象的形式，类似于以前的 mysql_fetch_object()</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">更多返回类型声明(PDOStatement::方法名)看手册。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">★插入，更新，删除数据，</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">$db->exec(“DELETE FROM `xxxx_menu` where mid=43″);</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">•  简单的总结一下上面的操作:</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">查询操作主要是PDO::query()、PDO::exec()、PDO::prepare()。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::query()主要是用于有记录结果返回的操作，特别是SELECT操作，</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::exec()主要是针对没有结果集合返回的操作，比如INSERT、UPDATE、DELETE等操作，它返回的结果是当前操作影响的列数。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDO::prepare()主要是预处理操作，需要通过$rs->execute()来执行预处理里面的SQL语句，这个方法可以绑定参数，功能比较强大，不是本文能够简单说明白的，大家可以参考手册和其他文档。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">获取结果集操作主要是：PDOStatement::fetchColumn()、PDOStatement::fetch()、PDOStatement::fetchALL()。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDOStatement::fetchColumn() 是获取结果指定第一条记录的某个字段，缺省是第一个字段。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDOStatement::fetch() 是用来获取一条记录，</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDOStatement::fetchAll()是获取所有记录集到一个中，获取结果可以通过PDOStatement::setFetchMode来设置需要结果集合的类型。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">另外有两个周边的操作，一个是PDO::lastInsertId()和PDOStatement::rowCount()。PDO::lastInsertId()是返回上次插入操作，主键列类型是自增的最后的自增ID。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">PDOStatement::rowCount()主要是用于PDO::query()和PDO::prepare()进行DELETE、INSERT、UPDATE操作影响的结果集，对PDO::exec()方法和SELECT操作无效。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">★事务和自动提交</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">至此，您已经通过 PDO 连接到了 mysql，在发出查询之前，您应该理解 PDO 是如何管理事务的。如果之前没有接触过事务，那么首先要知道事务的 4 个特征：原子性（Atomicity）、一致性（Consistency）、独立性（Isolation）和持久性（Durability），即 ACID。用外行人的话说，对于在一个事务中执行的任何工作，即使它是分阶段执行的，也一定可以保证该工作会安全地应用于数据库，并且在工作被提交时，不会受到来自其他连接的影响。事务性工作可以根据请求自动撤销（假设您还没有提交它），这使得脚本中的错误处理变得更加容易。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">事务通常是通过把一批更改积蓄起来、使之同时生效而实现的。这样做的好处是可以大大提高这些更新的效率。换句话说，事务可以使脚本更快，而且可能更健壮（不过需要正确地使用事务才能获得这样的好处）。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">0位粉丝         5楼</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">• 提供给预处理语句的参数不需要用引号括起来，驱动程序会处理这些。如果应用程序独占地使用预处理语句，那么可以确保没有 SQL 入侵发生。（然而，如果您仍然将查询的其他部分建立在不受信任的输入之上，那么就仍然存在风险）。</span><br style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;" /><span style="color: rgb(51, 51, 51); font-family: 'Segoe UI', Arial, sans-serif; font-size: 14px; line-height: 25px;">预处理语句是如此有用，以致 PDO 实际上打破了在目标 4 中设下的规则：如果驱动程序不支持预处理语句，那么 PDO 将仿真预处理语句。</span>

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<?php class PDO_db{  private $type;      private $host;  private $port;  private $user;  private $pass;  private $char;  private $db;  private $prodb;  public $stmt;  public function __construct($arr = array()){  $this ->type = isset($arr['type']) ? $arr['type'] : 'mysql';  $this ->host = isset($arr['host']) ? $arr['host'] : '127.0.0.1';  $this ->port = isset($arr['port']) ? $arr['port'] : '3306';  $this ->user = isset($arr['user']) ? $arr['user'] : 'root';  $this ->pass = isset($arr['pass']) ? $arr['pass'] : 'root';  $this ->char = isset($arr['char']) ? $arr['char'] : 'utf8';  $this ->db = isset($arr['db']) ? $arr['db'] : 'school';  $this ->conn();  $this ->dbexec("use {$this->db}");  $this ->dbexec("set names {$this ->char}"); }   private function conn(){  $this ->prodb=new PDO("{$this ->type}:host={$this ->host};port={$this ->port};dbname={$this ->db}",$this ->user,$this ->pass);      if(!$this ->prodb){die('数据库连接失败！');};      $this->prodb->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);    }   private function geterr($e){      echo 'SQL 请求出错<br/>'."错误：{$e->errorInfo[2]}<br/>line{$e->getLine()}";      exit;   }   private function dbexec($sql){   try{   return $this->prodb->exec($sql);   }catch(PDOException $e){   $this->geterr($e);   };   }    public function ins_del_db($sql){   $affect=$this->prodb->exec($sql);   $id=$this->prodb->lastinsertid();   return $id != 0?$id:$affect;      }   public function selectdb($sql){   try{   $this->stmt= $this->prodb->query($sql);   $arr=array();       while($res=$this->stmt->fetch(PDO::FETCH_ASSOC)){   $arr[]=$res;   };   return $arr;   }catch(PDOException $e){   $this->geterr($e);   };          }}header("content-type:text/html;charset=utf-8");$mydb=new PDO_db();//var_dump($mydb->ins_del_db("insert into pr_iuser values (null,'xiaoshan',{SHA1(789456)})"));echo '<pre>';var_dump($mydb->selectdb("select * from pr_student"));?>