PDO两个查询，一个用于查找结果的其他行？

Question

I currently do two queries when using prepared statements. One to fetch the results and another to fetch the number of found rows. I could previously do this with one query with mysql_num_rows. With larger queries i don't want to have to copy and paste the query and use COUNT every query. Is there a way to do this in one query like with mysql_num_rows?

 $connectdb->prepare("SELECT * FROM users WHERE username=:username");
        $connectdb->prepare("SELECT COUNT(*) FROM users WHERE username=:username");
    $query = $connectdb->execute(array(':username'=>$username));                                    
            $numrows = $query->fetchColumn();

             if($numrows!=0) {
               while(false !==($row = $query->fetch()))
               {

Answer 1

The statement already has the row count: PDOStatement::rowCount()

So use $query->rowCount(); and your first query only

PS: your code doesn't look like it even would work. The correct one should be:

$stmt = $connectdb->prepare("SELECT * FROM users WHERE username=:username");
$stmt->execute(array(':username'=>$username));                                    
...