Database interaction layer for PHP and MySql

DB

<?php
/**
 * Created by JetBrains PhpStorm.
 * User: Otar
 * Date: 2/22/13
 * Time: 8:02 AM
 * To change this template use File | Settings | File Templates.
 */
class DB {
    private $pdo_connection;

    function __construct() {
        try {
            $this->pdo_connection = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME, DB_USER, DB_PASSWORD);
            $this->pdo_connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
        } catch (PDOException $e) {
            print "<div class='db-error error'>Error!: " . $e->getMessage() . "<br/></div>";
            die();
        }
    }

    public function select($query) {
        $result = array();
        $query = $this->pdo_connection->prepare($query);
        $query->execute();
        while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
            $result[] = $row;
        }
        return $result;
    }

    /*
    * Implements simple sql insert
    *
    * $table - table name to insert into
    * $data - key => value array where keys are column names, values are data
    */
    public function insert($table, $data) {
        $result = array();
        $columns = array();
        $values = array();
        foreach ($data as $column => $value) {
            $columns[] = $column;
            $values[] = $value;
        }
        $columns_imploded = implode(",", $columns);
        $values_imploded = "'" . implode("','", $values) . "'";
        $query = "INSERT INTO  $table ($columns_imploded) VALUES($values_imploded)";
        $query = $this->pdo_connection->prepare($query);
        $result = $query->execute();
        return $this->pdo_connection->lastInsertId();
    }

    /*
     * Implements simple sql update
     *
     * $table - table name to update
     * $where - string containing sql piece of where logic
     * $data - key => value array where keys are column names, values are data
     */
    public function update($table, $where, $data) {
        $result = array();
        $new_values = array();
        foreach ($data as $column => $value) {
            $new_values[] = $column . " = " . "'" . $value . "'";
        }
        $new_values_sql = join(",", $new_values);
        $query = "UPDATE  $table
                SET $new_values_sql
                WHERE  $where ";
        $query = $this->pdo_connection->prepare($query);
        $result = $query->execute();
        return $result;
    }

    /*
     * Implements simple sql delete
     *
     * $table - table name where to delete
     * $where - string containing sql piece of where logic
     */
    public function delete($table, $where) {
        $result = "";
        $query = "DELETE  FROM $table
                WHERE  $where ";
        $query = $this->pdo_connection->prepare($query);
        $result = $query->execute();
        return $result;
    }
}