PHP/MySQL to PDO - php

Question

I want to change MySQL to PDO:
$mapa = mysql_fetch_array(mysql_query("select * from mapa where id = ".$postac['mapa']." limit 1"));
$mapa_d = mysql_query("select * from mapa_d where mapa = ".$mapa['id']." ");
PHP:
$_SESSION['postac'] = $_POST['postac'];
try like this so far:
$stmt = $pdo->prepare("SELECT * FROM mapa WHERE id=:mapa");
$stmt->bindValue(':mapa', $postac, PDO::PARAM_STR);
$stmt->EXECUTE();
$postac = $stmt->fetchAll(PDO::FETCH_ASSOC);
mysql update:
mysql_query("update postac set logged = 1 where id = ".$_SESSION['postac']." limit 1");
PDO:
$stmt = $pdo->prepare("update postac set logged = 1 where id:postac");
$stmt->bindValue(':postac', $_SESSION, PDO::PARAM_STR);
$stmt->EXECUTE();
$_SESSION = $stmt->fetchAll(PDO::FETCH_ASSOC);
Does not work.

Answer 1

Pre-Answer Note:
I assume you have already set up a PDO connection construct ($pdo) before trying to run your PDO queries.
$mapa = mysql_fetch_array(
mysql_query("select * from mapa WHERE id = ".$postac['mapa']." limit 1"));
$mapa_d = mysql_query("select * from mapa_d WHERE mapa = ".$mapa['id']." ");
PHP:
$_SESSION['postac'] = $_POST['postac'];
try like this so far:
$stmt = $pdo->prepare("SELECT * FROM mapa WHERE id=:mapa");
$stmt->bindValue(':mapa', $postac, PDO::PARAM_STR);
$stmt->EXECUTE();
$postac = $stmt->fetchAll(PDO::FETCH_ASSOC);
PART 1:
Be Consistent
Your original statement uses a value $postac['mapa'] as an id reference in the MySQL_ query, but then your PDO statement you are passing the whole array as a value into the PDO query.
First, MySQL: id ==> $postac['mapa']
Second, PDO: id ==> $postac
So this is causing an immediate issue as you're passing a whole array in to PDO which is somehow expected to extract one value from this array. This array is being classed as a string with your PDO::PARAM_STR declaration so this is preventing the query from using this value, as it doesn't fit what it's told to expect.
Therefore this returns a NULL query.
So to fix it,
$stmt = $pdo->prepare("SELECT * FROM mapa WHERE id=:mapa");
$stmt->bindValue(':mapa', $postac['mapa'], PDO::PARAM_STR);
$stmt->execute();
$postac = $stmt->fetchAll(PDO::FETCH_ASSOC);
Part 2:
Syntax
$stmt = $pdo->prepare("update postac set logged = 1 where id:postac");
$stmt->bindValue(':postac', $_SESSION, PDO::PARAM_STR);
$stmt->EXECUTE();
$_SESSION = $stmt->fetchAll(PDO::FETCH_ASSOC);
As above, you're passing the whole $_SESSION array as a PARAM_STR value, so it's returning VOID /NULL. You also have a syntax fault that you're using WHERE id:postac, but you really mean WHERE id = :postac be careful of missing out syntax such as = !!.
PART 3:
Error Checking
It is well worth exploring and learning how to get useful error feedback on PHP PDO, as it will save you posting to StackOverfow X times a day (hopefully!)!
There is a good answer here about how to setup PDO to output errors. It is also well worth browsing the PHP Manual for PDO error checking details.