Can't use pdo in class function using constructor - php

Question

suppose I have the class named as User and user is an object of that class,
now I call a function named as storevalues from user(an object of class User).
In the storevalues function,__construct function is called which assign the value to the class member.$this->name,$this->email,$this->password.
finally I try to store these values in DATABASE through PDO.
$conn = new PDO(DB_DSN,DB_USERNAME,DB_PASSWORD);
$sql="insert into user_info(name,email,password)values(:name,:email,:password)";
$st=$conn->prepare($sql);
$st->bindValue(":name",$this->name,PDO::PARAM_STR);
$st->bindValue(":email",$ths->email,PDO::PARAM_STR);
$st->bindValue(":password",$this->password,PDO::PARAM_STR);
$st->execute();
But the above code is not working.The connection is successfull made to the database but query is not executed.I want to know what mistake I have done in this code.
When I try assigning the class members value to the new variable then it works.The code below shows that method
$name=$this->name;
$email=$this->email;
$password=$this->password;
$conn = new PDO(DB_DSN,DB_USERNAME,DB_PASSWORD);
$sql="insert into user_info(name,email,password)values(:name,:email,:password)";
$st=$conn->prepare($sql);
$st->bindParam(":name",$name,PDO::PARAM_STR);
$st->bindParam(":email",$email,PDO::PARAM_STR);
$st->bindParam(":password",$password,PDO::PARAM_STR);
$st->execute();
I am a beginner in php and pdo and I know that my code is inefficient.Help me in finding the mistake in first method and identifying my mistakes.
User class
class User
{
public $name=null;
public $email=null;
public $password=null;
public function __construct($data=array())
{
if(isset($data['name']))
$this->name=$data['name'];
if(isset($data['email']))
$this->email=$data['email'];
if(isset($data['password']))
$this->password=$data['password'];
}
public function storevalues($result=array())
{
$this->__construct($result);
$conn = new PDO(DB_DSN,DB_USERNAME,DB_PASSWORD);
$sql="insert into user_info(name,email,password)values(:name,:email,:password)";
$st=$conn->prepare($sql);
$st->bindParam(":name",$this->name,PDO::PARAM_STR);
$st->bindParam(":email",$this->email,PDO::PARAM_STR);
$st->bindParam(":password",$this->password,PDO::PARAM_STR);
$st->execute();
}
}

Answer 1

You may catch the SQL error after the execute:
if ( ! $st->execute) {
Throw new exception('Mysql Error - ' . implode(',', $st->errorInfo()));
}