用户注册页面无法验证

<?php
    	
       

    $name = $_POST["name"];
    $age = $_POST["age"];
    $email = $_POST["email"];
    $password =$_POST["password"];

    $statement = mysqli_prepare($db, "INSERT INTO user_info(name,age,email,password) 
    VALUES
    (?,?,?,?)");  
    mysqli_stmt_bind_param($statement, "siss", $name, $age, $email, $password);
    mysqli_stmt_execute($statement);
     
      if($statement>0){
               $response["success"] = 1;
             }    
         else{
               $response["success"] = 0;
             }
        
         echo json_encode($response);



    ?><?php
    	
       

    $name = $_