PDO 增删改查封装的类

Selecting Data

你在mysql_*中是这样做的

 <?php
     $result = mysql_query('SELECT * from table') or die(mysql_error());

     $num_rows = mysql_num_rows($result);

     while($row = mysql_fetch_assoc($result)) {
         echo $row['field1'];
     }

你在pdo中可以这个样

<?php
    $stmt = $db->query('SELECT * FROM table');

    while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo $row['field1'];
    }

或者

<?php
    $result = mysql_query('SELECT * from table') or die(mysql_error());

    $num_rows = mysql_num_rows($result);

    while($row = mysql_fetch_assoc($result)) {
        echo $row['field1'];
    }

提示：如果你使用了方法像query（）。这个方法返回一个PDOStatement 对象，如果你想取出结果，请这样使用：

<?php
    foreach($db->query('SELECT * FROM table') as $row) {
        echo $row['field1'];
    }

PDO数据是通过->fetch() 方法获得的，这个方法是你的statement处理的。 
在fetch之前。最好告诉PDO这个数据你打算怎么fetch。在下个章节我会解释。

Fetch Modes

PDO::FETCH_ASSOC 可以在fetch() 和 fetchAll()中使用。 这个告诉PDO返回关联数组，字段的名字作为key。这还有很多fench方法。

首先我说明怎么选择fench 模式。

$stmt->fetch(PDO::FETCH_ASSOC)

在这里我用的是fetch，你也可以用：

• PDOStatement::fetchAll() 返回了一个数组包含了所有选择的行
• PDOStatement::fetchColumn() 返回下一行的一列作为结果集
• PDOStatement::fetchObject() 返回下一行作为一个对象
• PDOStatement::setFetchMode() 设置fetch模式

下面讨论fetch模式

• PDO::FETCH_ASSOC 关联数组
• PDO::FETCH_BOTH 默认的。返回关联数组和索引数组。 
  还有更多选项，可以阅读文档。

获取行的数量 
不是通过mysql_num_rows 而是通过rowCount()，比如说：

<?php
    $stmt = $db->query('SELECT * FROM table');
    $row_count = $stmt->rowCount();
    echo $row_count.' rows selected';

获取插入的id

<?php
    $result = $db->exec("INSERT INTO table(firstname, lastname) VAULES('John', 'Doe')");
    $insertId = $db->lastInsertId();

Insert and Update or Delete statements

在mysql_*中我们是这样做的

<?php
    $results = mysql_query("UPDATE table SET field='value'") or die(mysql_error());
    echo mysql_affected_rows($result);

在PDO中，同样可以这样：

<?php
    $affected_rows = $db->exec("UPDATE table SET field='value'");
    echo $affected_rows;

在上面的语句中，执行了一个sql语句并且返回受影响的行数。

上面的方法在你查询语句中没有变量时很好用。如果有变量，就应该使用 prepared statement or parameterized statement 。

Prepared Statements

Q：什么是 Prepared Statements，我为什么要用他？

A：Prepared Statement 是一条预编译的sql语句，可以被执行多次。

典型的使用Prepared Statement 工作流：

1. Prepare： 语句（statement）模版被application创建，发送到数据库管理系统（DBMS）。某些值仍然违背置顶，通过参数、占位符进行绑定

INSERT INTO PRODUCT (name, price) VALUES (?, ?)

1. DBMS进行解析、编译，得到最优的语句，把结果（语句）储存起来，并不执行。

2. 执行。过后，程序为参数提供或绑定值，DBMS执行语句（一般会返回一个结果）。程序或许会执行多次因为它有不同的值，想获得不同的结果。咱这个例子里，把Bread作为第一个参数，1.00作为第二个参数。

你可以通过引入占位符使用预编译语句。

Q：什么是命名占位符（named placeholders ），怎么使用呢？

A：命名占位符，用过一个冒号而不是？ 这样就不用去操心问号的顺序问题了

$stmt->bindParam(':bla', $bla);

<?php
    $stmt = $db->prepare("SELECT * FROM table WHERE id=:id AND name=:name");
    $stmt->execute(array(':name' => $name, ':id' => $id));
    $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);

另一个对于OOP（面向对象编程）很友好的就是，命名占位符可以直接插入到你的对象，再然后加入到你的数据库。假设属性与字段相同

class person {
    public $name;
    public $add;
    function __construct($a,$b) {
        $this->name = $a;
        $this->add = $b;
    }

}
$demo = new person('john','29 bla district');
$stmt = $db->prepare("INSERT INTO table (name, add) value (:name, :add)");
$stmt->execute((array)$demo);

Q：好了，什么是匿名占位符(unnamed placeholders)，怎么使用？

A：看个例子。

<?php
    $stmt = $db->prepare("INSERT INTO folks (name, add) values (?, ?)");
    $stmt->bindValue(1, $name, PDO::PARAM_STR);
    $stmt->bindValue(2, $add, PDO::PARAM_STR);
    $stmt->execute();
$stmt = $db->prepare("INSERT INTO folks (name, add) values (?, ?)");
 $stmt->execute(array('john', '29 bla district'));

　　

注意：在匿名占位符我们一定要注意在数组中的顺序，在PDOStatement::execute() 方法中。

SELECT, INSERT, UPDATE, DELETE prepared queries

1. select

$stmt = $db->prepare("SELECT * FROM table WHERE id=:id AND name=:name");
$stmt->execute(array(':name' => $name, ':id' => $id));
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);

1. insert

$stmt = $db->prepare("INSERT INTO table(field1,field2) VALUES(:field1,:field2)");
$stmt->execute(array(':field1' => $field1, ':field2' => $field2));
$affected_rows = $stmt->rowCount();

1. delete

$stmt = $db->prepare("DELETE FROM table WHERE id=:id");
$stmt->bindValue(':id', $id, PDO::PARAM_STR);
$stmt->execute();
$affected_rows = $stmt->rowCount();

1. update

$stmt = $db->prepare("UPDATE table SET name=? WHERE id=?");
$stmt->execute(array($name, $id));
$affected_rows = $stmt->rowCount();

注意：

PDO和Mysqli也不是完全的安全。有机会会翻译一遍这个文章，这里就简单说一下：

$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$pdo->query('SET NAMES GBK');
$stmt = $pdo->prepare("SELECT * FROM test WHERE name = ? LIMIT 1");
$stmt->execute(array(chr(0xbf) . chr(0x27) . " OR 1=1 /*"));

下面是一个封装的类

 class CPdo{
  protected $_dsn = "mysql:host=localhost;dbname=test";
  protected $_name = "root";
  protected $_pass = "";
  protected $_condition = array();
  protected $pdo;
  protected $fetchAll;
  protected $query;
  protected $result;
  protected $num;
  protected $mode;
  protected $prepare;
  protected $row;
  protected $fetchAction;
  protected $beginTransaction;
  protected $rollback;
  protected $commit;
  protected $char;
  private static $get_mode;
  private static $get_fetch_action;
  /**
  *pdo construct
  */
  public function __construct($pconnect = false) {
   $this->_condition = array(PDO::ATTR_PERSISTENT => $pconnect);
   $this->pdo_connect();
  }
  /**
  *pdo connect
  */
  private function pdo_connect() {
   try{
    $this->pdo = new PDO($this->_dsn,$this->_name,$this->_pass,$this->_condition);
   }
   catch(Exception $e) {
    return $this->setExceptionError($e->getMessage(), $e->getline, $e->getFile);
   }
  }
  /**
  *self sql get value action
  */
  public function getValueBySelfCreateSql($sql, $fetchAction = "assoc",$mode = null) {
   $this->fetchAction = $this->fetchAction($fetchAction);
   $this->result = $this->setAttribute($sql, $this->fetchAction, $mode);
   $this->AllValue = $this->result->fetchAll();
   return $this->AllValue;
  }
  /**
  *select condition can query
  */
  private function setAttribute($sql, $fetchAction, $mode) {
   $this->mode = self::getMode($mode);
   $this->fetchAction = self::fetchAction($fetchAction);
   $this->pdo->setAttribute(PDO::ATTR_CASE, $this->mode);
   $this->query = $this->base_query($sql);
   $this->query->setFetchMode($this->fetchAction);
   return $this->query;
  }
  /**
  *get mode action
  */
  private static function getMode($get_style){
   switch($get_style) {
    case null:
     self::$get_mode = PDO::CASE_NATURAL;
    break;
    case true:
     self::$get_mode = PDO::CASE_UPPER;
    break;
    case false;
    self::$get_mode= PDO::CASE_LOWER;
    break;
   }
   return self::$get_mode;
  }
  /**
  *fetch value action
  */
  private static function fetchAction($fetchAction) {
   switch($fetchAction) {
    case "assoc":
     self::$get_fetch_action = PDO::FETCH_ASSOC; //asso array
    break;
    case "num":
     self::$get_fetch_action = PDO::FETCH_NUM; //num array
    break;
    case "object":
     self::$get_fetch_action = PDO::FETCH_OBJ; //object array
    break;
    case "both":
     self::$get_fetch_action = PDO::FETCH_BOTH; //assoc array and num array
    break;
    default:
     self::$get_fetch_action = PDO::FETCH_ASSOC;
    break;
   }
   return self::$get_fetch_action;
  }
  /**
  *get total num action
  */
  public function rowCount($sql) {
   $this->result = $this->base_query($sql);
   $this->num = $this->result->rowCount();
   return $this->num;
  }
  /*
  *simple query and easy query action
  */
  public function query($table, $column = "*",$condition = array(), $group = "",$order = "", $having = "", $startSet = "",$endSet = "",$fetchAction = "assoc",$params = null){
   $sql = "select ".$column." from `".$table."` ";
   if ($condition != null) {
    foreach($condition as $key=>$value) {
     $where .= "$key = '$value' and ";
    }
    $sql .= "where $where";
    $sql .= "1 = 1 ";
   }
   if ($group != "") {
    $sql .= "group by ".$group." ";
   }
   if ($order != "") {
    $sql .= " order by ".$order." ";
   }
   if ($having != "") {
    $sql .= "having '$having' ";
   }
   if ($startSet != "" && $endSet != "" && is_numeric($endSet) && is_numeric($startSet)) {
    $sql .= "limit $startSet,$endSet";
   }
   $this->result = $this->getValueBySelfCreateSql($sql, $fetchAction, $params);
   return $this->result;
  }
  /**
  *execute delete update insert and so on action
  */
  public function exec($sql) {
   $this->result = $this->pdo->exec($sql);
   $substr = substr($sql, 0 ,6);
   if ($this->result) {
    return $this->successful($substr);
   } else {
    return $this->fail($substr);
   }
  }
  /**
  *prepare action
  */
  public function prepare($sql) {
   $this->prepare = $this->pdo->prepare($sql);
   $this->setChars();
   $this->prepare->execute();
   while($this->rowz = $this->prepare->fetch()) {
    return $this->row;
   }
  }
  /**
  *USE transaction
  */
  public function transaction($sql) {
   $this->begin();
   $this->result = $this->pdo->exec($sql);
   if ($this->result) {
    $this->commit();
   } else {
    $this->rollback();
   }
  }
  /**
  *start transaction
  */
  private function begin() {
   $this->beginTransaction = $this->pdo->beginTransaction();
   return $this->beginTransaction;
  }
  /**
  *commit transaction
  */
  private function commit() {
   $this->commit = $this->pdo->commit();
   return $this->commit;
  }
  /**
  *rollback transaction
  */
  private function rollback() {
   $this->rollback = $this->pdo->rollback();
   return $this->rollback;
  }
  /**
  *base query
  */
  private function base_query($sql) {
   $this->setChars();
   $this->query = $this->pdo->query($sql);
   return $this->query;
  }
  /**
  *set chars
  */
  private function setChars() {
   $this->char = $this->pdo->query("SET NAMES 'UTF8'");
   return $this->char;
  }
  /**
  *process sucessful action
  */
  private function successful($params){
   return "The ".$params." action is successful";
  }
  /**
  *process fail action
  */
  private function fail($params){
   return "The ".$params." action is fail";
  }
  /***进程异常动作
  *process exception action
  */
  private function setExceptionError($getMessage, $getLine ,$getFile) {
   echo "Error message is ".$getMessage."<br /> The Error in ".$getLine." line <br /> This file dir on ".$getFile;
   exit();
  }
 }

封装类2

 <?php
 /**
  */

 //使用pdo连接数据库 封装增删改查

 class DB{

 //定义私有属性
 private $host;
 private $port;
 private $username;
 private $password;
 private $dbname;
 private $charset;
 private $dbtype;
 private $pdo;

 //定义构造函数自动加载配置文件
 function __construct(){
 //加载配置文件
 include_once('./config/config.php');

 //给属性赋值
 $this->dbtype = $config['db'];
         $this->host  = $config['host'];
         $this->username = $config['username'];
         $this->password = $config['password'];
         $this->charset = $config['charset'];
         $this->port = $config['port'];
         $this->dbname = $config['dbname'];

 //pdo连接数据库
 $this->pdo = new PDO("$this->dbtype:host=$this->host;dbname=$this->dbname","$this->username","$this->password");
 //发送编码
 $this->pdo->query("set names $this->charset");
     }

 /**
      *   定义执行查询sql语句的方法
      *   参数： 查询sql语句
      *   返回： 二维关联数组
      */
 public function query($sql){
         $res = $this->pdo->query($sql);
         $res->setFetchMode(PDO::FETCH_ASSOC);
         $arr = $res->fetchAll();
 return $arr;
     }

 /**
      *   查询一行记录的方法
      *   参数：表名  条件(不包含where)
      *   返回：一维关联数组
      */
 public function getRow($tablename,$where){
 //组装sql语句
 $sql = "select * from $tablename where $where";
 //查询
 $res = $this->pdo->query($sql);
         $res->setFetchMode(PDO::FETCH_ASSOC);
         $arr = $res->fetch();
 return $arr;
     }

 /**
      *   查询全部记录
      *   参数：表名
      *   返回：二维关联数组
      */
 public function getAll($tablename){
         $res = $this->pdo->query("select * from $tablename");
         $res->setFetchMode(PDO::FETCH_ASSOC);
         $arr = $res->fetchAll();
 return $arr;
     }

 /**
      *   查询某个字段
      *   参数： 字段名(多个的话用逗号隔开) 表名 条件（不含where）
      *   返回： 二维关联数组
      */
 public function getOne($column,$tablename,$where="1"){
 //拼接sql语句
 $sql = "select $column from $tablename where $where";
         $rs = $this->pdo->query($sql);
         $rs->setFetchMode(PDO::FETCH_ASSOC);
 //$col = $rs->fetchColumn();
 $col = $rs->fetchAll();
 return  $col;
     }

 /**
      *   查询最后一次插入的数据
      *   参数：表名
      *   返回：数组
     */
 public function getlastone($tablename){
         $sql = "select * from $tablename where id=(select max(id) from $tablename)";
         $res = $this->pdo->query($sql);
         $res->setFetchMode(PDO::FETCH_ASSOC);
         $arr = $res->fetch();
 return $arr;
     }

 /**
      *  向数据库中添加一条信息
      *  参数：表名 一维关联数组
      *  返回: 布尔值
      */
 public function insert($tablename,$arr){
 //拿到数组之后先处理数组  过滤字段
         //取出表中的字段
 $sql = "select COLUMN_NAME from information_schema.COLUMNS where table_name = '$tablename' and table_schema ='$this->dbname'";
         $columns = $this->pdo->query($sql);
         $columns->setFetchMode(PDO::FETCH_ASSOC);
         $columns = $columns->fetchAll();
         $cols = array(); //存储表中的全部字段
 foreach($columns as $key=>$val){
             $cols[] = $val['COLUMN_NAME'];
         }
 //将要入库的数组进行键值分离
 $keys = array();
         $values = '';
 foreach($arr as $k=>$v){
 if(!in_array($k,$cols)){
 unset($arr[$k]);
             }else{
                 $keys[] = $k;
                 $values .= "'".$v."',";
             }
         }
         $column = implode(',',$keys);
         $values = substr($values,0,-1);
 //拼接sql语句
 $sql = "insert into $tablename($column) values ($values)";
         $res = $this->pdo->exec($sql);
 return $res;
     }

 /**
      *   删除数据 其实就是改变字段值使之不被查询
      *   参数：表名 条件(不含where)
      *   返回：布尔
     */
 public function delete($tablename,$where){
         $sql = "update $tablename set is_del=1 where $where";
         $res = $this->pdo->exec($sql);
 return $res;
     }

 /**
      *   修改数据
      *   参数：表名  要修改的数据的数组
      *   返回：布尔
     */
 public function update($tablename,$arr,$where){
 //处理传过来的数组
 $str = "";
 foreach($arras $k=>$v){
             $str .= "$k='".$v."',";
         }
 //截取字符串
 $str = substr($str,0,-1);
 //拼接sql语句
 $sql = "update $tablename set $str where $where";
         $res = $this->pdo->exec($sql);
 return $res;
     }
 }