php实战第五天_PHP教程

php单态设计模式，我的理解，类中创建静态变量，使其只有一个，使用方法进行返回对象，该方法 检查对象是存在不存在就创建。从而实现单一对象。

将__construct()设置为private这样就new不了咯.self是本类的意思。“::”调用静态方法

 

 

[php]      /**
    * 
    */ 
    class myclass 
    { 
        static private $db_class; 
        static public function getClass() 
        { 
            if (is_null(self::$db_class)) { 
                self::$db_class=new myclass(); 
                echo "创建对象咯"; 
            }else{ 
                echo "返回原来的对象"; 
                return self::$db_class; 
            } 
        } 
        private function __construct() 
        { 
            echo "11111111111111"; 
        } 
 
        public function __destruct(){ 
            echo "
aaaaaaaaaaaa"; 
        } 
        public function show(){ 
            echo "bbbbbbbbbbbbbbb"; 
        } 
    } 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a=myclass::getClass(); 
    $a->show(); 
 
 
    /*//直接new 会报错的噢!!!
    new myclass();
    new myclass();
 
    new myclass();
    new myclass();
 
    new myclass();
    new myclass();
    new myclass();
    new myclass();*/ 
 ?> 

 /**
 *
 */
 class myclass
 {
  static private $db_class;
  static public function getClass()
  {
   if (is_null(self::$db_class)) {
    self::$db_class=new myclass();
    echo "创建对象咯";
   }else{
    echo "返回原来的对象";
    return self::$db_class;
   }
  }
  private function __construct()
  {
   echo "11111111111111";
  }

  public function __destruct(){
   echo "
aaaaaaaaaaaa";
  }
  public function show(){
   echo "bbbbbbbbbbbbbbb";
  }
 }
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a=myclass::getClass();
 $a->show();

 /*//直接new 会报错的噢!!!
 new myclass();
 new myclass();

 new myclass();
 new myclass();

 new myclass();
 new myclass();
 new myclass();
 new myclass();*/
 ?>

 

 

 

 

 

 

这个是小例子.下面给出 单态的 mysql类

[php]  // +----------------------------------------------------------------------  
// |MySQL操作类  
// +----------------------------------------------------------------------  
// |@微凉 QQ:496928838  
// +----------------------------------------------------------------------  
class MySQL{ 
     
    private $db_mysql_hostname; 
    private $db_mysql_username; 
    private $db_mysql_password; 
    private $db_mysql_database; 
    private $db_mysql_port; 
    private $db_mysql_charset; 
     
    private $query_list = array(); 
     
    //查询次数  
    public $query_count = 0; 
    //查询开始时间  
    public $query_start_time; 
     
    //当前查询ID  
    protected $queryID; 
    //当前连接  
    protected $conn; 
    // 事务指令数  
    protected $transTimes = 0; 
    // 返回或者影响记录数  
    protected $numRows    = 0; 
    // 错误信息  
    protected $error      = ''; 
     
    //静态实例  
    static private $db_class; 
    //取得本类  
    static public function getClass() 
    { 
      if (is_null(self::$db_class)) { 
            self::$db_class=new MySQL(); 
        } 
        return self::$db_class; 
    } 
 
    //定义为私有方法就new起来咯,要用 getClass  
    private function __construct() 
    { 
             
    } 
 
 
    public function connect($hostname_or_conf,$username,$password,$database,$port = '3306',$char = 'utf8'){ 
        if(is_array($hostname_or_conf)){ 
            $this->db_mysql_hostname = $hostname_or_conf['hostname']; 
            $this->db_mysql_username = $hostname_or_conf['username']; 
            $this->db_mysql_password = $hostname_or_conf['password']; 
            $this->db_mysql_database = $hostname_or_conf['database']; 
            $this->db_mysql_port = isset($hostname_or_conf['port'])?$hostname_or_conf['port']:'3306'; 
            $this->db_mysql_charset = isset($hostname_or_conf['charset'])?$hostname_or_conf['charset']:'utf8'; 
        }elseif(!empty($hostname_or_conf)||!empty($username)||!empty($password)||!empty($database)) 
        { 
             $this->db_mysql_hostname = $hostname_or_conf; 
             $this->db_mysql_username = $username; 
             $this->db_mysql_password = $password; 
             $this->db_mysql_database = $database; 
             $this->db_mysql_port = $port; 
             $this->db_mysql_charset = $char; 
              
        }else{ 
            die('configuration error.'); 
        } 
         
        $server = $this->db_mysql_hostname.':'.$this->db_mysql_port; 
        $this->conn = mysql_connect($server,$this->db_mysql_username,$this->db_mysql_password,true) or die('Connect MySQL DB error!'); 
        mysql_select_db($this->db_mysql_database,$this->conn) or die('select db error!'); 
        mysql_query("set names " . $this->db_mysql_charset, $this->conn); 
 
    } 
 
 
 
 
    /**
     +----------------------------------------------------------
     * 设置数据对象值
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     *table,where,order,limit,data,field,join,group,having
     +----------------------------------------------------------
     */ 
    public function table($table){ 
        $this->query_list['table'] = $table; 
        return $this; 
    } 
     
    public function where($where){ 
        $this->query_list['where'] = $where; 
        return $this; 
    } 
     
    public function order($order){ 
        $this->query_list['order'] = $order; 
        return $this; 
    } 
     
    public function limit($offset,$length=null){ 
        if (is_null($length)) { 
            $this->query_list['limit']='limit '.$offset; 
            return $this; 
        }else { 
            if(!isset($length)){ 
                $length = $offset; 
                $offset = 0; 
            } 
                $this->query_list['limit'] = 'limit '.$offset.','.$length; 
                return $this; 
        } 
 
    } 
     
    public function data($data){ 
        //读取数据表字段,然后处理表单数据  
        $dataList = $this->getFields($this->query_list['table']); 
        $arr=array(); 
        foreach ($dataList as $key=>$value) { 
            if (array_key_exists ($key,$data) ) { 
                $arr[$key]=$data[$key]; 
            } 
             
        } 
        //var_dump($arr);  
        /*
        if(is_object($data)){
            $data   =   get_object_vars($data);
        }elseif (is_string($data)){
            parse_str($data,$data);
        }elseif(!is_array($data)){
            //Log:DATA_TYPE_INVALID
        }
        */ 
        $this->query_list['data'] = $arr; 
        return $this; 
    } 
    public function field($fields){ 
        $this->query_list['fields'] = $fields; 
        return $this; 
    } 
    public function join($join){ 
        $this->query_list['join'] = $join; 
        return $this; 
    } 
    public function group($group){ 
        $this->query_list['group'] = $group; 
        return $this; 
    } 
    public function having($having){ 
        $this->query_list['having'] = $having; 
        return $this; 
    } 
    /**
     +----------------------------------------------------------
     * 查询
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
    public function select(){ 
        $select_sql = 'select '; 
        $fields = isset($this->query_list['fields'])?$this->query_list['fields']:'*'; 
        $select_sql.=$fields; 
        $select_sql.= ' from `'.$this->query_list['table'].'` '; 
         
        isset($this->query_list['join'])?($select_sql.=$this->query_list['join']):''; 
        isset($this->query_list['where'])?($select_sql.=' where '.$this->query_list['where']):''; 
        isset($this->query_list['group'])?($select_sql.=' group by'.$this->query_list['group']):''; 
        isset($this->query_list['having'])?($select_sql.=' mysql having '.$this->query_list['having']):''; 
        isset($this->query_list['order'])?($select_sql.=' order by '.$this->query_list['order']):''; 
        isset($this->query_list['limit'])?($select_sql.=' '.$this->query_list['limit']):''; 
    //  echo '----->'.$select_sql;  
        return $this->query($select_sql); 
    } 
    /**
     +----------------------------------------------------------
     * 增加
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
    public function add(){ 
        $add_sql = 'insert into `'.$this->query_list['table'].'` ('; 
         
        $data = $this->query_list['data']; 
        $value = $field = ''; 
        foreach($data as $k=>$v){ 
            $field .= '`'.$k.'`,'; 
            if(is_numeric($v)) 
                $value .= $v.','; 
            else 
                $value .= '\''.$v.'\','; 
        } 
        $add_sql .= rtrim($field,',').') values ('.rtrim($value,',').')'; 
 
    //  echo 'add_sql'.$add_sql;  
        return $this->execute($add_sql); 
    } 
    /**
     +----------------------------------------------------------
     * 删除
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
    public function delete(){ 
        $del_sql = 'delete from `'.$this->query_list['table'].'` where '.$this->query_list['where']; 
         
        if(isset($this->query_list['order'])) 
            $del_sql .= 'order by '.$this->query_list['order']; 
        if(isset($this->query_list['limit'])) 
            $del_sql .= ' '.$this->query_list['limit']; 
             
        return $this->execute($del_sql); 
         
    } 
    /**
     +----------------------------------------------------------
     * 更新
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
    public function update(){ 
        $update_sql = 'update `'.$this->query_list['table'].'` set '; 
        $data = $this->query_list['data']; 
         
        foreach($data as $k=>$v){ 
            if(is_numeric($v)) 
                $update_sql .= '`'.$k.'` ='.$v.','; 
            else 
                $update_sql .= '`'.$k.'` =\''.$v.'\','; 
        } 
        $update_sql = rtrim($update_sql,','); 
        if(isset($this->query_list['where'])) 
            $update_sql .= ' where '.$this->query_list['where']; 
        if(isset($this->query_list['order'])) 
            $update_sql .= ' order by '.$this->query_list['order']; 
        if(isset($this->query_list['limit'])) 
            $update_sql .= ' '.$this->query_list['limit']; 
         
        return $this->execute($update_sql); 
         
    } 
     /**
     +----------------------------------------------------------
     * 执行查询 返回数据集
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param string $sql  sql指令
     */ 
    public function query($sql) { 
        if ( !$this->conn ) return false; 
        $this->queryStr = $sql; 
        //释放前次的查询结果  
        if ( $this->queryID ) {    $this->free();    } 
         
        $this->query_start_time = microtime(true); 
         
        $this->queryID = mysql_query($sql, $this->conn); 
        $this->query_count++; 
        if ( false === $this->queryID ) { 
            $this->error(); 
            return false; 
        } else { 
            $this->numRows = mysql_num_rows($this->queryID); 
            return $this->getAll(); 
        } 
    } 
    /**
     +----------------------------------------------------------
     * 执行语句
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param string $sql  sql指令
     +----------------------------------------------------------
     */ 
    public function execute($sql) { 
        if ( !$this->conn ) return false; 
        $this->queryStr = $sql; 
        //释放前次的查询结果  
        if ( $this->queryID ) {    $this->free();    } 
         
        $this->query_start_time = microtime(true); 
         
        $result =   mysql_query($sql, $this->conn) ; 
        $this->query_count++; 
        if ( false === $result) { 
            $this->error(); 
            return false; 
        } else { 
            $this->numRows = mysql_affected_rows($this->conn); 
            return $this->numRows; 
        } 
    } 
    /**
     +----------------------------------------------------------
     * 获得所有的查询数据
     +----------------------------------------------------------
     * @access private
     +----------------------------------------------------------
     * @return array
     */ 
    private function getAll() { 
        //返回数据集  
        $result = array(); 
        if($this->numRows >0) { 
            while($row = mysql_fetch_assoc($this->queryID)){ 
                $result[]   =   $row; 
            } 
            mysql_data_seek($this->queryID,0); 
        } 
        return $result; 
    } 
    /**
     +----------------------------------------------------------
     * 取得数据表的字段信息
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     */ 
    public function getFields($tableName) { 
        $result =   $this->query('SHOW COLUMNS FROM `'.$tableName.'`'); 
        $info   =   array(); 
        if($result) { 
            foreach ($result as $key => $val) { 
                $info[$val['Field']] = array( 
                    'name'    => $val['Field'], 
                    'type'    => $val['Type'], 
                    'notnull' => (bool) ($val['Null'] === ''), // not null is empty, null is yes  
                    'default' => $val['Default'], 
                    'primary' => (strtolower($val['Key']) == 'pri'), 
                    'autoinc' => (strtolower($val['Extra']) == 'auto_increment'), 
                ); 
            } 
        } 
        return $info; 
    } 
    /**
     +----------------------------------------------------------
     * 取得数据库的表信息
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     */ 
    public function getTables($dbName='') { 
        if(!empty($dbName)) { 
           $sql    = 'SHOW TABLES FROM '.$dbName; 
        }else{ 
           $sql    = 'SHOW TABLES '; 
        } 
        $result =   $this->query($sql); 
        $info   =   array(); 
        foreach ($result as $key => $val) { 
            $info[$key] = current($val); 
        } 
        return $info; 
    } 
 
    /**
     +----------------------------------------------------------
     * 最后次操作的ID
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
     public function last_insert_id(){ 
        return mysql_insert_id($this->conn); 
    } 
    /**
     * 执行一条带有结果集计数的
     */ 
    public function count($sql){ 
        return $this->execute($sql); 
    } 
    /**
     +----------------------------------------------------------
     * 启动事务
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @return void
     +----------------------------------------------------------
     */ 
    public function startTrans() { 
        if ($this->transTimes == 0) { 
            mysql_query('START TRANSACTION', $this->conn); 
        } 
        $this->transTimes++; 
        return ; 
    } 
 
    /**
     +----------------------------------------------------------
     * 提交事务
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @return boolen
     +----------------------------------------------------------
     */ 
    public function commit() 
    { 
        if ($this->transTimes > 0) { 
            $result = mysql_query('COMMIT', $this->conn); 
            $this->transTimes = 0; 
            if(!$result){ 
                throw new Exception($this->error()); 
            } 
        } 
        return true; 
    } 
 
    /**
     +----------------------------------------------------------
     * 事务回滚
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @return boolen
     +----------------------------------------------------------
     */ 
    public function rollback() 
    { 
        if ($this->transTimes > 0) { 
            $result = mysql_query('ROLLBACK', $this->conn); 
            $this->transTimes = 0; 
            if(!$result){ 
                throw new Exception($this->error()); 
            } 
        } 
        return true; 
    } 
    /**
     +----------------------------------------------------------
     * 错误信息
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
     public function error() { 
        $this->error = mysql_error($this->conn); 
        if('' != $this->queryStr){ 
            $this->error .= "\n [ SQL语句 ] : ".$this->queryStr; 
        } 
        return $this->error; 
    } 
    /**
     +----------------------------------------------------------
     * 释放查询结果
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     */ 
    public function free() { 
        @mysql_free_result($this->queryID); 
        $this->queryID = 0; 
        $this->query_list = null; 
    } 
    /**
     +----------------------------------------------------------
     * 关闭连接
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param 
     +----------------------------------------------------------
     */ 
    function close(){ 
        if ($this->conn && !mysql_close($this->conn)){ 
            throw new Exception($this->error()); 
        } 
        $this->conn = 0; 
        $this->query_count = 0; 
    } 
    /**
     +----------------------------------------------------------
     * 析构方法
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     */ 
    function __destruct(){ 
         $this->close(); 
    } 
} 

// +----------------------------------------------------------------------
// |MySQL操作类
// +----------------------------------------------------------------------
// |@微凉 QQ:496928838
// +----------------------------------------------------------------------
class MySQL{
 
 private $db_mysql_hostname;
 private $db_mysql_username;
 private $db_mysql_password;
 private $db_mysql_database;
 private $db_mysql_port;
 private $db_mysql_charset;
 
 private $query_list = array();
 
 //查询次数
 public $query_count = 0;
 //查询开始时间
 public $query_start_time;
 
 //当前查询ID
 protected $queryID;
 //当前连接
 protected $conn;
 // 事务指令数
 protected $transTimes = 0;
 // 返回或者影响记录数
    protected $numRows    = 0;
    // 错误信息
    protected $error      = '';
 
    //静态实例
    static private $db_class;
    //取得本类
    static public function getClass()
    {
      if (is_null(self::$db_class)) {
            self::$db_class=new MySQL();
        }
        return self::$db_class;
    }

    //定义为私有方法就new起来咯,要用 getClass
    private function __construct()
    {
           
    }

    public function connect($hostname_or_conf,$username,$password,$database,$port = '3306',$char = 'utf8'){
        if(is_array($hostname_or_conf)){
            $this->db_mysql_hostname = $hostname_or_conf['hostname'];
            $this->db_mysql_username = $hostname_or_conf['username'];
            $this->db_mysql_password = $hostname_or_conf['password'];
            $this->db_mysql_database = $hostname_or_conf['database'];
            $this->db_mysql_port = isset($hostname_or_conf['port'])?$hostname_or_conf['port']:'3306';
            $this->db_mysql_charset = isset($hostname_or_conf['charset'])?$hostname_or_conf['charset']:'utf8';
        }elseif(!empty($hostname_or_conf)||!empty($username)||!empty($password)||!empty($database))
        {
             $this->db_mysql_hostname = $hostname_or_conf;
             $this->db_mysql_username = $username;
             $this->db_mysql_password = $password;
             $this->db_mysql_database = $database;
             $this->db_mysql_port = $port;
             $this->db_mysql_charset = $char;
            
        }else{
            die('configuration error.');
        }
       
        $server = $this->db_mysql_hostname.':'.$this->db_mysql_port;
        $this->conn = mysql_connect($server,$this->db_mysql_username,$this->db_mysql_password,true) or die('Connect MySQL DB error!');
        mysql_select_db($this->db_mysql_database,$this->conn) or die('select db error!');
        mysql_query("set names " . $this->db_mysql_charset, $this->conn);

    }

 

 /**
     +----------------------------------------------------------
     * 设置数据对象值
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     *table,where,order,limit,data,field,join,group,having
     +----------------------------------------------------------
     */
 public function table($table){
  $this->query_list['table'] = $table;
  return $this;
 }
 
 public function where($where){
  $this->query_list['where'] = $where;
  return $this;
 }
 
 public function order($order){
  $this->query_list['order'] = $order;
  return $this;
 }
 
 public function limit($offset,$length=null){
  if (is_null($length)) {
   $this->query_list['limit']='limit '.$offset;
   return $this;
  }else {
   if(!isset($length)){
    $length = $offset;
    $offset = 0;
   }
    $this->query_list['limit'] = 'limit '.$offset.','.$length;
    return $this;
  }

 }
 
 public function data($data){
  //读取数据表字段,然后处理表单数据
  $dataList = $this->getFields($this->query_list['table']);
  $arr=array();
  foreach ($dataList as $key=>$value) {
   if (array_key_exists ($key,$data) ) {
    $arr[$key]=$data[$key];
   }
   
  }
  //var_dump($arr);
  /*
  if(is_object($data)){
   $data   =   get_object_vars($data);
  }elseif (is_string($data)){
   parse_str($data,$data);
  }elseif(!is_array($data)){
   //Log:DATA_TYPE_INVALID
  }
  */
  $this->query_list['data'] = $arr;
  return $this;
 }
 public function field($fields){
  $this->query_list['fields'] = $fields;
  return $this;
 }
 public function join($join){
  $this->query_list['join'] = $join;
  return $this;
 }
 public function group($group){
  $this->query_list['group'] = $group;
  return $this;
 }
 public function having($having){
  $this->query_list['having'] = $having;
  return $this;
 }
 /**
     +----------------------------------------------------------
     * 查询
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param
     +----------------------------------------------------------
     */
 public function select(){
  $select_sql = 'select ';
  $fields = isset($this->query_list['fields'])?$this->query_list['fields']:'*';
  $select_sql.=$fields;
  $select_sql.= ' from `'.$this->query_list['table'].'` ';
  
  isset($this->query_list['join'])?($select_sql.=$this->query_list['join']):'';
  isset($this->query_list['where'])?($select_sql.=' where '.$this->query_list['where']):'';
  isset($this->query_list['group'])?($select_sql.=' group by'.$this->query_list['group']):'';
  isset($this->query_list['having'])?($select_sql.=' mysql having '.$this->query_list['having']):'';
  isset($this->query_list['order'])?($select_sql.=' order by '.$this->query_list['order']):'';
  isset($this->query_list['limit'])?($select_sql.=' '.$this->query_list['limit']):'';
 // echo '----->'.$select_sql;
  return $this->query($select_sql);
 }
 /**
     +----------------------------------------------------------
     * 增加
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param
     +----------------------------------------------------------
     */
 public function add(){
  $add_sql = 'insert into `'.$this->query_list['table'].'` (';
  
  $data = $this->query_list['data'];
  $value = $field = '';
  foreach($data as $k=>$v){
   $field .= '`'.$k.'`,';
   if(is_numeric($v))
    $value .= $v.',';
   else
    $value .= '\''.$v.'\',';
  }
  $add_sql .= rtrim($field,',').') values ('.rtrim($value,',').')';

 // echo 'add_sql'.$add_sql;
  return $this->execute($add_sql);
 }
 /**
     +----------------------------------------------------------
     * 删除
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param
     +----------------------------------------------------------
     */
 public function delete(){
  $del_sql = 'delete from `'.$this->query_list['table'].'` where '.$this->query_list['where'];
  
  if(isset($this->query_list['order']))
   $del_sql .= 'order by '.$this->query_list['order'];
  if(isset($this->query_list['limit']))
   $del_sql .= ' '.$this->query_list['limit'];
   
  return $this->execute($del_sql);
  
 }
 /**
     +----------------------------------------------------------
     * 更新
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param
     +----------------------------------------------------------
     */
 public function update(){
  $update_sql = 'update `'.$this->query_list['table'].'` set ';
  $data = $this->query_list['data'];
  
  foreach($data as $k=>$v){
   if(is_numeric($v))
    $update_sql .= '`'.$k.'` ='.$v.',';
   else
    $update_sql .= '`'.$k.'` =\''.$v.'\',';
  }
  $update_sql = rtrim($update_sql,',');
  if(isset($this->query_list['where']))
   $update_sql .= ' where '.$this->query_list['where'];
  if(isset($this->query_list['order']))
   $update_sql .= ' order by '.$this->query_list['order'];
  if(isset($this->query_list['limit']))
   $update_sql .= ' '.$this->query_list['limit'];
  
  return $this->execute($update_sql);
  
 }
  /**
     +----------------------------------------------------------
     * 执行查询 返回数据集
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param string $sql  sql指令
     */
    public function query($sql) {
        if ( !$this->conn ) return false;
        $this->queryStr = $sql;
        //释放前次的查询结果
        if ( $this->queryID ) {    $this->free();    }
       
        $this->query_start_time = microtime(true);
       
        $this->queryID = mysql_query($sql, $this->conn);
        $this->query_count++;
        if ( false === $this->queryID ) {
            $this->error();
            return false;
        } else {
            $this->numRows = mysql_num_rows($this->queryID);
            return $this->getAll();
        }
    }
 /**
     +----------------------------------------------------------
     * 执行语句
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     * @param string $sql  sql指令
     +----------------------------------------------------------
     */
    public function execute($sql) {
        if ( !$this->conn ) return false;
        $this->queryStr = $sql;
        //释放前次的查询结果
        if ( $this->queryID ) {    $this->free();    }
       
        $this->query_start_time = microtime(true);
       
        $result =   mysql_query($sql, $this->conn) ;
        $this->query_count++;
        if ( false === $result) {
            $this->error();
            return false;
        } else {
            $this->numRows = mysql_affected_rows($this->conn);
            return $this->numRows;
        }
    }
 /**
     +----------------------------------------------------------
     * 获得所有的查询数据
     +----------------------------------------------------------
     * @access private
     +----------------------------------------------------------
     * @return array
     */
    private function getAll() {
        //返回数据集
        $result = array();
        if($this->numRows >0) {
            while($row = mysql_fetch_assoc($this->queryID)){
                $result[]   =   $row;
            }
            mysql_data_seek($this->queryID,0);
        }
        return $result;
    }
 /**
     +----------------------------------------------------------
     * 取得数据表的字段信息
     +----------------------------------------------------------
     * @access public
     +----------------------------------------------------------
     */
    public function getFields($tableName) {
        $result =   $this->query('SHOW COLUMNS FROM `'