( ! ) Warning: PDOStatement::execute

<?php

function post($title,$content,$posted){
 global $db;

 $p = [
  'title' => $title,
  'content' => $content,
  'writer' => $_SESSION['administrateur'],
  'posted' => $posted
  

 ];
 $sql= "INSERT INTO posts (title,content,writer,date,posted) VALUES ('title','content','writer','NOW()','posted')";
 

 $req=$db->prepare($sql);
 $req->execute($p);
 
}


function post_img($tmp_name, $extension){

 global $db;
 $id= $db->lastInsertId();
 $i=[
  'id' =>  $id,
  'image' => $id.$extension
 ];
 $sql="UPDATE posts SET image = :image WHERE id= :id";
 $req = $db->prepare($sql);
 $req->execute($i);
 move_uploaded_file($tmp_name,"../img/posts/".$id.$extension);
 header("Location:index.php?page=post&id=".$id);
}