2 test

2->|->page->
            |->header.php
            |->body.php
   |->index.php
   |->connect.php
   |->guestbook.php
   |->search.php
   |->view.php

index.php:
<?php
include 'page/header.php';
include 'page/body.php';
include 'view.php';
?>

header.php:
<html>
<title>Guest Book</title>
<head>
    <meta charset="UTF-8">
</head>

body.php:

<body>
<div align="center">
    <h1>Гостевая книга</h1>
    <div class="book">

    </div>
</div>
<form name="search" method="post" action="../search.php">
    <input type="search" name="query" placeholder="Поиск">
    <button type="submit">Найти</button>
</form>
<form name="test" method="post" action="../guestbook.php">
    <p><b>Ваше имя:</b><br>
        <input type="text" name="username" size="40">
    </p>
    <p><b>Ваш e-mail</b><Br>
        <input type="text" name="mail" size="40">
    </p>
    <p><b>Ваш город</b><Br>
        <input type="text" name="city" size="40">
    </p>
    <p><b>Ваш телефон</b><Br>
        <input type="text" name="phone" size="40">
    </p>
    <p>Комментарий<Br>
        <textarea name="comment" cols="140" rows="3"></textarea></p>
    <p><input type="submit" value="Отправить">
        <input type="reset" value="Очистить"></p>
</form>
</body>
</html>

connect.php:
<?php
$user = "root";
$password = "admin123";
$dbConnect = new PDO('mysql:host=localhost;dbname=guest', $user, $password);
?>

guestbook.php:
<?php
include 'connect.php';

$data = array("name"=> $_POST['username'],
              "mail"=>$_POST['mail'],
              "city"=>$_POST['city'],
              "phone"=>$_POST['phone'],
              "comment"=>$_POST['comment']);
$insertDb = $dbConnect->query("INSERT INTO guestbook (username, mail, city, phone, comment, datetime) VALUES ('".$data['name']."','".$data['mail']."','".$data['city']."','".$data['phone']."','".$data['comment']."', CURRENT_TIMESTAMP);");

view.php:
<?php
include 'connect.php';
$query = "SELECT * FROM guestbook";
$data = $dbConnect->query($query);
$result = $data->fetchAll();
foreach ($result as $row){
    echo $row['id']."</br>",
        $row['username']."</br>",
        $row['mail']."</br>",
        $row['city']."</br>",
        $row['phone']."</br>",
        $row['comment']."</br>",
        $row['datetime']."</br>"."</br>";
}
?>

search.php:
<?php
include 'page/header.php';
include 'page/body.php';
include 'connect.php';
$search = $_POST['query'];
$query = "SELECT * FROM guestbook WHERE username LIKE :search OR mail like :search OR city like :search OR phone like :search or comment like :search";
$stmt = $dbConnect->prepare($query);
$stmt->bindValue(':search','%'.$search. '%' , PDO::PARAM_INT);
$stmt->execute();
if($stmt ->rowCount() > 0) {
    $result = $stmt->fetchAll();
    foreach ($result as $row){
        echo $row['id']."</br>",
            $row['username']."</br>",
            $row['mail']."</br>",
            $row['city']."</br>",
            $row['phone']."</br>",
            $row['comment']."</br>",
            $row['datetime']."</br>"."</br>";
    }
}
else {
    echo 'no found';
}

?>