PHP封装PDO之单例模式实现增删改查

DB类

class Db{
    
    //存储 类的实例化对象
    private  static $instance;
 
    //存储pdo类的实例化
    private  $pdo;
 
    //存储PDOStament
    private $stmt;
 
    //禁止外部 new 类
    private function __construct($config,$port,$charset){
        try{
            $this->pdo = new  PDO('mysql:host='.$config['host'].';dbname='.$config['dbname'].';port='.$port.';charset='.$charset,$config['user'],$config['password']);
            //$this->pdo ->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
        }catch(PDOException $e){
            header("Content-type: text/html;charset=utf-8"); 
            echo 'mysql connect error：'.$e->getMessage();
        }
    }
    
    //对外访问的方法  实现 类的实例    
    public static function getInstance($config,$port=3306,$charset="utf8"){        
        //判断是否有实例化 没有实例化 有 直接返回实例化
        if(!self::$instance instanceof Db ) self::$instance = new self($config,$port,$charset);        
        return self::$instance;        
    }
    
    //插入数据
    public function insertData($table,$data){        
        //拼接插入的字段名
        $columns = implode(',',array_keys($data));
        //拼接占位符
        $values = ':'.implode(',:',array_keys($data));        
        $sql = "INSERT INTO $table ($columns) VALUES($values)";
        $newData = $this->doData($data);
        $this->exe($sql,$newData);
        if($this->stmt->errorCode()==00000) return $this->pdo->lastInsertId();
        else return $this->stmt->errorInfo()[2];        
    }
    
    //更新数据    
    public function updateData($table,$data,$where){
        //$sql = "UPDATE user SET user_name=:name WHERE id=:id";        
        //加个判断 判断$where是否在数据表存在
        $res = $this->getData($table,array_keys($data),$where);
        if(!$res) return '不存在你要更新的数据';        
        $columns = '';
        foreach($data as $k=>$v) $columns.=$k.'=:'.$k.',';
        $columns = trim($columns,',');        
        $sql = "UPDATE $table SET $columns ".$where;
        $newData = $this->doData($data);
        $this->exe($sql,$newData);        
        if($this->stmt->errorCode()==00000) return 1;            
        else return $this->stmt->errorInfo()[2];        
    }
 
    // 查询数据
    public function getData($table,$fields,$where=null,$one=true){
        if(count($fields)>1) $columns = implode(',',array_values($fields));            
        else $columns = $fields[0];
        $sql = "SELECT $columns FROM $table ".$where;
        $this->exe($sql);
        if($this->stmt->errorCode()==00000){
            if($one) return $this->stmt->fetch(PDO::FETCH_ASSOC);
            else return $this->stmt->fetchAll(PDO::FETCH_ASSOC);            
        }else return $this->stmt->errorInfo()[2];
    }    
 
    //删除数据    
    public function deleteData($table,$where){
        if(!$where) return '缺少删除条件';
        $sql = "DELETE FROM $table ".$where;
        $res = $this->getData($table,['*'],$where);
        if(!$res) return '不存在你要删除的数据';        
        $this->exe($sql);          
        if($this->stmt->errorCode()==00000) return 1;            
        else return $this->stmt->errorInfo()[2];
    }
        
    //处理插入的数据    
    private function doData($data){
        foreach($data as $k=>$v){
            $key = ':'.$k;
            $newData[$key]=$v;
        }
        return $newData;
    }
    
    //执行sql语句
    private function exe($sql,$data=null){
        $this->stmt = $this->pdo->prepare($sql);
        $this->stmt->execute($data);
    }
    
    //禁止外部 克隆对象
    private function __clone(){}    
}

单例模式：私有的构造方法，私有的静态属性，共有的静态getInstance（）方法获取对象。

插入数据方法：insertData（$table,$data）参数是表名，和数据。

更新数据方法：updateData($table,$data,$where) 参数是表名，数据还有条件。

删除数据方法：deleteData($table,$where) 参数是表名，和条件。

查询数据方法：getData($table,$fields,$where=null,$one=true) 参数是表名，查询字段，条件，还有是是否查询单条数据。

具体调用方法：

require_once(dirname(__FILE__)."/db/Db.php");
$config=['host'=>'127.0.0.1','dbname'=>'test','user'=>'root','password'=>'root'];
$db = Db::getInstance($config);
 
$table = 'user';
// 插入数据
$data = ['user_name'=>'asdfasdfasdasdf','password'=>'asdfasd'];
echo $db->insertData($table,$data);
// 更新数据
echo $db->updateData($table,$data,' where id=7');
$fields = ['user_name','password'];
//查询单条
var_dump($db->getData($table,$fields,'WHERE id=2',true));
//查询多条
var_dump($db->getData($table,$fields));
 
//删除数据
var_dump($db->deleteData($table,'WHERE id=2'));

如另外文件调用:

require_once(dirname(__FILE__)."/db/DB.php");
$config=['host'=>'xx.xxx.com','dbname'=>'sjk','user'=>'ua','password'=>'123123'];
$GLOBALS['$db']=Db::getInstance($config);  //定义为全局变量