How to manipulate data from the database using PDO

Question

I’m starting to use PDO in my PHP projects. When I worked with mysql, without PDO, when I took a query in the BD, I was able to get each data associated to a variable and could do what I wanted with it. Now using PDO, how can I do this data manipulation?

For an example: I would do that..

$contas_entrada = mysql_query("SELECT valor FROM entrada WHERE id_empresa='$id_empresa' ORDER BY data DESC");
while($entrada_row = mysql_fetch_array($contas_entrada)){
$valor = $entrada_row['valor'];
}

Then I could work on the $value variable to work on it. How can I get data, via PDO, to manipulate them?

Answer 1

It is not difficult to convert the code:

$sql = "SELECT valor FROM entrada WHERE id_empresa = :id ORDER BY data DESC";
$stmt = $pdo->prepare($sql);
if($stmt->execute(array(':id' => $id))){
    print_r($stmt->errorInfo);
}

$itens = $stmt->fetchAll(PDO::FETCH_ASSOC);

$total = 0;
foreach($itens as $item){
    $total += $item['valor'];
}

Or you can use the while/fetch variant()

$total = 0;
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
    $total += $row['valor'];
}