PHP数据库助手类

<?php
 /*
  对数据库操作的助手类
  */

 class SqlHelper{
  
  private $conn;
  private $host="127.0.0.1";
  private $username="root";
  private $password="123";
  private $database="emp";
  /**
  * @return the $conn
  */
 public function getConn() {
  return $this->conn;
 }

  /**
  * @return the $host
  */
 public function getHost() {
  return $this->host;
 }

  /**
  * @return the $username
  */
 public function getUsername() {
  return $this->username;
 }

  /**
  * @return the $password
  */
 public function getPassword() {
  return $this->password;
 }

  /**
  * @return the $database
  */
 public function getDatabase() {
  return $this->database;
 }
 
 public function __construct(){
   $this->conn=new mysqli($this->host,$this->username,$this->password,$this->database);
   if(mysqli_connect_error()){
    die("数据库连接错误".$this->conn->error);
   }
  }
  
 //执行DQL语句
 public function Execute_DQL($sql){
   $arr=array();
   $res=$this->conn->query($sql);
   $i=0;
   while($row=$res->fetch_assoc()){
    $arr[$i++]=$row;
   }
   return $arr;
   $res->free_result();
  }
 public  function Execute_DQL_Array($sql){
  $arr=array();
  $res=$this->conn->query($sql);
  $i=0;
  while($row=$res->fetch_array()){
   $arr[$i++]=$row;
  }
  return $arr;
  $res->free_result();
 }
  
 //关闭连接
 public function Close(){
   $this->conn->close();
  }
  
 //执行DML语句
 public function Execute_DML($sql){
   $this->conn->query($sql);
   echo $this->conn->affected_rows;
 }
  
 }
?>