$sql_posts = "SELECT post_id, post
FROM posts
WHERE user_id = :userid";
$result = $con->prepare($sql);
$result->bindParam(':userid', $_SESSION['user-id'], PDO::PARAM_INT);
$result->execute();
$posts_array = $result->fetchAll(PDO::FETCH_ASSOC);
print_r($posts_array);
/*
run:
Array ( [0] => Array ( [post_id] => 1 [post] => C is popular programming language )
[1] => Array ( [post_id] => 2 [post] => PHP is popular server-side scripting )
[2] => Array ( [post_id] => 3 [post] => PHP version 7 is available )
[3] => Array ( [post_id] => 4 [post] => PHP new post ) )
*/