<?php
    class Bd_Conexao
    {

       private static $instancia = NULL;
       private $server = SERVER;
       private $user = USER;
       private $password =PASSWORD ;
       public static $conexao;


       protected function __construct()
       {
            if(self::$conexao==NULL){

               self::$conexao = mysqli_connect($this->server, $this->user, $this->password) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
               @mysqli_set_charset( self::$conexao, "utf8");
           }
       }

      //Singleton
       public static function getInstancia()
       {
           if(self::$instancia==NULL)       {
             self::$instancia = new self;
           }
           return self::$instancia;
       }

       public function query($sql)
       {
           $result = mysqli_query(self::$conexao,$sql) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return $result;
        }

       public function prepare($sql)
       {
           $result = mysqli_prepare(self::$conexao,$sql) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return $result;
       }

       public function multiquery($sql)
       {
           $r = mysqli_multi_query(self::$conexao,$sql) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return $r;
        }

       public function select_db($db)
       {
           $r = mysqli_select_db(self::$conexao, $db) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return  $r;
        }

      //TRANSACTIONS
       public function transaction()
       {
           $r = mysqli_autocommit(self::$conexao, FALSE) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return  $r;
        }

        public function commit()
       {
           $r = mysqli_commit(self::$conexao) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return  $r;
        }

        public function rollback()
       {
           $r = mysqli_rollback(self::$conexao) or die("erro: ".mysqli_error(self::$conexao)." num: ".mysqli_errno(self::$conexao));
           return  $r;
        }

        public function __destruct()
       {
           if(self::$conexao){mysqli_close(self::$conexao) or die("Houve um erro ao fechar a conexão"); }
           return $r;
       }
    }