Alternative for mysql_num_rows using PDO

问题

Right now I have a PHP file that does a MYSQL query and then counts rows like this:

$count=mysql_num_rows($result);


if ($count == 1) {
    $message = array('status' => 'ok');
} else {
    $message = array('status' => 'error');
}

This works fine but I'm trying to change all my PHP files to use PDO. So how can this be done with PDO?

回答1:

$res = $DB->query('SELECT COUNT(*) FROM table');
$num_rows = $res->fetchColumn();

or

$res = $DB->prepare('SELECT COUNT(*) FROM table');
$res->execute();
$num_rows = $res->fetchColumn();

You can use this to ask if data exists or is selected, too:

$res = $DB->query('SELECT COUNT(*) FROM table');
$data_exists = ($res->fetchColumn() > 0) ? true : false;

Or with your variables:

$res = $DB->query('SELECT COUNT(*) FROM table');
$message = ($res->fetchColumn() > 0) ? array('status' => 'ok') : array('status' => 'error');

回答2:

$stmt = $db->query('SELECT * FROM table');  
$row_count = $stmt->rowCount();  
echo $row_count.' rows selected';

回答3:

Maybe you can use PDO's "fetchAll" method, which returns an array containing all the SELECT results. Then use "count" method to count the array's rows.

Ex:

$rows = $stmt->fetchAll();
$num_rows = count($rows);

回答4:

If you are not using prepared statements then try:

$find = $dbh->query('SELECT count(*) from table');
if ($find->fetchColumn() > 0){
    echo 'found';
}

However, if you choose prepared statements, which i highly recommend, then:

$find = $dbh->prepare('SELECT count(*) from table');
$find->execute();
if ($find->fetchColumn() > 0){
    echo 'found';
}

回答5:

Can be like that...

$numRows = $conn->query("SELECT COUNT(*) FROM yourtable")->fetchColumn();
echo $numRows; 

来源：https://stackoverflow.com/questions/11305230/alternative-for-mysql-num-rows-using-pdo