Ajax and encapsulation into class

<! DOCTYPE html Public"-//w3c//dtd XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >$ (document). Ready (function(e) {$ ("#btn"). Click (function(){                varUID = $ ("#uid").Val (); varPWD = $ ("#pwd").Val (); $.Ajax ({URL: "Chuli.php",//process the path of the pagedata:{u:uid,p:pwd,type:0},//the data passedType: "POST",//How data is submitted for deliveryDataType: "TEXT",//type of return value, text,json,xml three types selectableSuccessfunction(data) {//callback function//check if error display function$ ("#erro"). HTML (Date); if(data== "OK") {window. location = "main.php"; }                Else{alert (data);                }                                }                        }); })                //determine if the user name is available$ ("#user"). Blur (function(){                        varUID = $ (this).Val (); $.Ajax ({URL: "Chuli.php",Data: {u:uid,type:1},type: "POST",DataType: "TEXT",Success:function(d) {if(d== "OK")                    {                        $("#ts"). HTML ("User name available"); }                    Else                    {                        $("#ts"). HTML ("<span style= ' color:red ' > the username already exists! </span> ");                        }                                        }                                }); })            });</script>
<! DOCTYPE html Public"-//w3c//dtd XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >$ (document). Ready (function(e) {$ ("#btn"). Click (function(){                $.Ajax ({URL: "Chuli.php",Data: {Type:2},type: "POST",DataType: "TEXT",Success:function(data) {varHang = data.Split("|"); varstr = "";  for(vari=0;i)                {                    varLie = Hang[i].Split("^"); STR= str+ "<option value= '" +lie[0]+ ">" +lie[1]+ "</option>"; }                                $("#sel").html (str);                }                        }); })        });</script>
<?PHP$type=$_post["Type"];include("dbda.php");$db=NewDbda ();Switch($type){     Case0:$uid=$_post["U"]; $pwd=$_post["P"]; $sql= "SELECT count (*) from login where Username= ' {$uid} ' and password= ' {$pwd}‘"; $attr=$db->query ($sql); if($attr[0] [0]==0)        {            Echo"User name password is not correct!" "; }        Else        {            Echo"OK"; }         Break;  Case1:$uid=$_post["U"]; $sql= "SELECT count (*) from login where Username= ' {$uid}‘"; $attr=$db->query ($sql); if($attr[0] [0] = = 0)        {            Echo"OK"; }        Else        {            Echo"NO"; }                 Break;  Case2:$sql= "SELECT * FROM Nation"; $attr=$db->query ($sql); //n001^ han |n002^ hui |n003^ Miao        $str="";  for($i= 0;$i<Count($attr);$i++)        {                         for($j= 0;$j<Count($attr[$i]);$j++)            {                $str=$str.$attr[$i][$j]; $str=$str." ^"; }            $str=substr($str, 0,strlen($str)-1); $str=$str."|"; }        $str=substr($str, 0,strlen($str)-1); Echo $str;  Break; }
Encapsulation class
<?PHPclassajax{//The method of the Ajax call//sql is the statement to execute//$type is the type of SQL statement, 0 for adding and removing, 1 for querying//$db representing the data to be manipulated     Public functionAjax ($sql,$type=1,$db= "Testa")         {        //Connecting Objects        $conn=NewMysqli ($this->host,$this->uid,$this->pwd,$db); //determine if the connection is successful!Mysqli_connect_error() or die("Connection Failed"); //Execute SQL statement        $result=$conn->query ($sql); $attr=$result-Fetch_all (); //to spell an array into a string                        $str= ""; if($type==1){             for($i= 0;$i<Count($attr);$i++)            {                     for($j= 0;$j<Count($attr[$i]);$j++)                {                    $str=$str.$attr[$i][$j]; $str=$str." ^"; }                $str=substr($str, 0,strlen($str)-1); $str=$str."|"; }                $str=substr($str, 0,strlen($str)-1); return $str." <br> "; }            Else            {                return $result; }    }            }
Ajax and encapsulation into class