The fifth day of php practice_PHP tutorial

PHP monomorphic design mode, my understanding is to create a static variable in the class so that there is only one, and use a method to return the object. This method checks whether the object exists before creating it. Thus achieving a single object.

Set __construct() to private so that new cannot be used. Self is the meaning of this class. "::" calls static method

[php] /**
    * 
   */
class myclass
{
         static private $db_class;
          static public function getClass()
                                                                  If (is_null(self::$db_class)) {
                    self::$db_class=new myclass();
                       echo "Create object";
              }else{
echo "Return to the original object";
                    return self::$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();


/*//If you use new directly, an error will be reported!!!
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::$db_class=new myclass();
echo "Create object";
}else{
echo "Return to the original object";
Return self::$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();

/*//If you use new directly, an error will be reported!!!
new myclass();
new myclass();

new myclass();
new myclass();

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

This is a small example. The monomorphic mysql class is given below

[php] // +-------------------------------------------------- -----------------------
// |MySQL operation class
// +-------------------------------------------------- -----------------------
// |@微梁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();
       
//Number of queries
Public $query_count = 0;
//Query start time
Public $query_start_time;
       
//Current query ID
protected $queryID;
//Current connection
protected $conn;
// Number of transaction instructions
protected $transTimes = 0;
// Return or affect the number of records
protected $numRows = 0;
// Error message
protected $error = '';
       
//Static instance
static private $db_class;
//Get this category
static public function getClass()
{
If (is_null(self::$db_class)) {
               self::$db_class=new MySQL();
         } 
         return self::$db_class;
}  

//If it is defined as a private method, it will be new. Use 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); 
 
    } 
 
 
 
 
    /**
+------------------------------------------------- ----------
* Set data object value
+------------------------------------------------- ----------
* @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; 
    } 
    /**
+------------------------------------------------- ----------
* Query
+------------------------------------------------- ----------
* @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); 
    } 
    /**
+------------------------------------------------- ----------
* Delete
+------------------------------------------------- ----------
* @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); 
         
    } 
    /**
+------------------------------------------------- ----------
* Update
+------------------------------------------------- ----------
* @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); 
         
    } 
     /**
+------------------------------------------------- ----------
* Execute the query and return the data set
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param string $sql sql command
​​*/ 
    public function query($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(); 
        } 
    } 
    /**
+------------------------------------------------- ----------
* Execution statement
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param string $sql sql command
+------------------------------------------------- ----------
​​*/ 
    public function execute($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; 
        } 
    } 
    /**
+------------------------------------------------- ----------
* Get all query data
+------------------------------------------------- ----------
* @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 $result; 
    } 
    /**
+------------------------------------------------- ----------
* Get the field information of the data table
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
​​*/ 
    public function getFields($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; 
    } 
 
    /**
+------------------------------------------------- ----------
* The ID of the last operation
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param
+------------------------------------------------- ----------
​​*/ 
     public function last_insert_id(){ 
        return mysql_insert_id($this->conn); 
    } 
    /**
* Execute a
with result set count ​​*/ 
    public function count($sql){ 
        return $this->execute($sql); 
    } 
    /**
+------------------------------------------------- ----------
* Start transaction
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @return void
+------------------------------------------------- ----------
​​*/ 
    public function startTrans() { 
        if ($this->transTimes == 0) { 
            mysql_query('START TRANSACTION', $this->conn); 
        } 
        $this->transTimes++; 
        return ; 
    } 
 
    /**
+------------------------------------------------- ----------
* Submit transaction
+------------------------------------------------- ----------
* @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; 
    } 
 
    /**
+------------------------------------------------- ----------
* *Transaction rollback
+------------------------------------------------- ----------
* @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; 
    } 
    /**
+------------------------------------------------- ----------
* Error message
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param
+------------------------------------------------- ----------
​​*/ 
     public function error() { 
        $this->error = mysql_error($this->conn); 
        if('' != $this->queryStr){ 
            $this->error .= "n [ SQL语句 ] : ".$this->queryStr; 
        } 
        return $this->error; 
    } 
    /**
+------------------------------------------------- ----------
* Release query results
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
​​*/ 
    public function free() { 
        @mysql_free_result($this->queryID); 
        $this->queryID = 0; 
        $this->query_list = null; 
    } 
    /**
+------------------------------------------------- ----------
*Close connection
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param
+------------------------------------------------- ----------
​​*/ 
    function close(){ 
        if ($this->conn && !mysql_close($this->conn)){ 
            throw new Exception($this->error()); 
        } 
        $this->conn = 0; 
        $this->query_count = 0; 
    } 
/**
+------------------------------------------------- ----------
* Destruction method
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
​​*/
Function __destruct(){
$this->close();
}  
}

// +-------------------------------------------------- -----------------------
// |MySQL operation class
// +-------------------------------------------------- -----------------------
// |@微梁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();

//Number of queries
public $query_count = 0;
//Query start time
public $query_start_time;

//Current query ID
protected $queryID;
//Current connection
protected $conn;
//Number of transaction instructions
protected $transTimes = 0;
//Return or affect the number of records
protected $numRows = 0;
// Error message
protected $error = '';

//Static instance
static private $db_class;
//Get this category
​ static public function getClass()
{
If (is_null(self::$db_class)) {
               self::$db_class=new MySQL();
}
          return self::$db_class;
}

//If it is defined as a private method, it will be new. Use 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);

    }

 

 /**
+------------------------------------------------- ----------
* Set data object value
+------------------------------------------------- ----------
* @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;
 }
 /**
+------------------------------------------------- ----------
* Query
+------------------------------------------------- ----------
* @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);
 }
 /**
+------------------------------------------------- ----------
* Add
+------------------------------------------------- ----------
* @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);
 }
 /**
+------------------------------------------------- ----------
* Delete
+------------------------------------------------- ----------
* @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);
  
 }
 /**
+------------------------------------------------- ----------
* Update
+------------------------------------------------- ----------
* @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);
  
 }
  /**
+------------------------------------------------- ----------
* Execute the query and return the data set
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param string $sql sql command
​​*/
    public function query($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();
        }
    }
 /**
+------------------------------------------------- ----------
* Execution statement
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
* @param string $sql sql command
+------------------------------------------------- ----------
​​*/
    public function execute($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;
        }
    }
 /**
+------------------------------------------------- ----------
* Get all query data
+------------------------------------------------- ----------
* @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 $result;
    }
 /**
+------------------------------------------------- ----------
* Get the field information of the data table
+------------------------------------------------- ----------
* @access public
+------------------------------------------------- ----------
​​*/
    public function getFields($tableName) {
        $result =   $this->query('SHOW COLUMNS FROM `'