<?php
$host = "localhost";
$username = "root";
$password = "";
$baza = "lab11";

$conn = @new mysqli($host, $username, $password, $baza);
if ($conn->connect_error) {
    die('Wystapil blad podczas laczenia: ' . $conn->connect_errno);
}
$conn->query("set names utf8");

$sql = "insert into posty (id_kategorii, tytul, tresc) value (".$_POST['cat'].",'".$_POST['title']."','".$_POST['content']."')";

if($conn->query($sql) === TRUE){
    header("Location: index.php");
}else{
    echo "blad ".$sql;
}

$conn->close();