Example of php implementing mysql encapsulation class

<?php
class Mysql {
 private $host;
 private $user;
 private $pwd;
 private $dbName;
 private $charset;
 private $conn = null;
 public function __construct() {
  $this->host = &#39;localhost&#39;;
  $this->user = &#39;root&#39;;
  $this->pwd = &#39;root&#39;;
  $this->dbName = &#39;test&#39;;
  $this->connect($this->host,$this->user,$this->pwd);
  $this->switchDb($this->dbName);
  $this->setChar($this->charset);
 }
 //负责链接
 private function connect($h,$u,$p) {
  $conn = mysql_connect($h,$u,$p);
  $this->conn = $conn;
 }
 //负责切换数据库
 public function switchDb($db) {
  $sql = &#39;use&#39; . $db;
  $this->query($sql);
 }
 //负责设置字符集
 public function setChar($char) {
  $sql = &#39;set names&#39; . $char;
  $this->query($sql);
 }
 //负责发送sql查询
 public function query($sql) {
  return mysql_query($sql,$this->conn);
 }
 //负责获取多行多列的select结果
 public function getAll($sql) {
  $list = array();
  $rs = $this->query($sql);
  if (!$rs) {
   return false;
  }
  while ($row = mysql_fetch_assoc($rs)) {
   $list[] = $row;
  }
  return $list;
 }
 public function getRow($sql) {
  $rs = $this->query($sql);
  if(!$rs) {
   return false;
  }
  return mysql_fetch_assoc($rs);
 }
 public function getOne($sql) {
  $rs = $this->query($sql);
  if (!$rs) {
   return false;
  }
  return mysql_fetch_assoc($rs);
  return $row[0];
 }
 public function close() {
  mysql_close($this->conn);
 }
}
echo &#39;<pre class="brush:php;toolbar:false">&#39;;
$mysql = new Mysql();
print_r($mysql);
$sql = "insert into stu values (4,&#39;wangwu&#39;,&#39;99998&#39;)";
if($mysql->query($sql)){
 echo "query成功";
}else {
 echo "失败";
}
echo "<br />";
$sql = "select * from stu";
$arr = $mysql->getAll($sql);
print_r($arr);
?>