PDO相当于mysql_num_rows

Question

I want to be able to translate the mysql code below into PDO equivalent. Please can someone help me out as I have looked around and tried other examples but they are not working for me.

// Count Participants
$result = mysql_query("SELECT * FROM table2");
$num_rows = mysql_num_rows($result);

Answer 1

You can either just issue a count query to the DB

$db    = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
$count = $db->query('SELECT count(*) FROM table2')->fetchColumn();

or get an array back that can be counted

$stmt  = $db->query('SELECT * FROM table2');
$rows  = $stmt->fetchAll(PDO::FETCH_ASSOC);
$count = count( $rows );

or get any kind of other resultset back, and count that etc.