<?php
        class MySQL{
            private static $conn;
            private $host;
            private $user;
            private $pass;
            private $bd;

            public function __construct($host, $user, $pass, $bd){
                $this->host = $host;
                $this->user = $user;
                $this->pass = $pass;
                $this->bd   = $bd;
                $this->connect();
            }

            //Conexão com banco de dados
            public function connect(){
                if(!$conn = mysql_connect($this->host, $this->user, $this->pass)){
                    die('Erro ao conectar :'.mysql_error());
                }else{
                    if(!mysql_select_db($this->db, $conn)){
                    die('Erro ao selecionar :'.mysql_error());
                    }
                }
            }
            //executa o SQL
            public function query($sql){
                    if(!$query = mysql_query($sql)){
                        die('Erro executar query :'.mysql_error());
                    }else{
                        return $query;
                    }

            }
            //inseri dados
            public function insert($table, array $data){
                $strSQL = "INSERT INTO %s (%s) VALUES(%s)";
                $value = array();
                foreach($data as $k => $v){
                    $value[] = sprintf("'%s'", $this->escape($v));
                }
                $strSQL = sprintf($strSQL, $table, implode(', ', array_keys($data)), implode(', ', $value));
                $this->query($strSQL);
            }

            //altera dados
            public function update($table, array $data, array $where){
                $strSQL = "UPDATE %s SET %s WHERE %s";
                $field  = array();
                $fieldW = array();
                foreach($data as $k => $v){
                     $field[] = sprintf("%s='%s'", $k, $this->escape($v));
                }
                foreach($where as $k => $v){
                    $fieldW[] =  sprintf("%s='%s'", $k, $this->escape($v));
                }
                $strSQL = sprintf($strSQL, $table, implode(', ',  $field), implode(' AND', $fieldW));
                $this->query($strSQL);
            }

            //excluir dados
            public function delete($table, array $where){
                $strSQL = "DELETE FROM %s WHERE %s";
                $field  = array();
                foreach($where as $k => $v){
                    $field[] =  sprintf("%s='%s'", $k, $this->escape($v));
                }
                $strSQL = sprintf($strSQL, $table, implode(' AND ',  $field));
                $this->query($strSQL);
            }

            //resume a execução dos comandos INSERT, UPDATE, DELETE

            public function execute($type, $table, $data=null, $where = null){
                    swicth($type){
                        case 'insert':
                            $this->insert($table, $data);
                        break;
                        case 'update':
                            $this->update($table, $data, $where);
                        break;

                        case 'delete':
                            $this->update($table, $where);
                        break;
                    }
            }


            //escapa a string
            public function escape($value){
                return mysql_real_escape_string(stripslashes($value));
            }
        }

        //********************************UTILIZANDO******************************************//

        $mysql = new MySQL('localhost', 'root', '', 'banco_de_dados');
        //INSERIR DADOS
        $data  = array('nome' => 'David', 'estado' =>'rj');
        $mysql->execute('insert', 'contato', $data);
        //ALTERAR DADOS
        $data  = array('nome' => 'David CHC', 'estado' =>'RJ');
        $where = array("id" => 15);
        $mysql->execute('update', 'contato', $data, $where);
        //EXCLUIR DADOS

        $where = array("id" => 4);
        $mysql->execute('delete', 'contato', null, $where);
?>