如何在一个php页面中创建2个或更多PDO对象？

Question

Hi I have a code which there is a pdo object like this :

$db = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $db_username, $db_password);

thats good but When I want to creat another PDO object wiht a different name i into same page like this :

$dbh = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $db_username, $db_password);
$notification_array = $dbh -> prepare("select * from `machines`ORDER BY id DESC limit 51 ");

php says :

 Catchable fatal error: Object of class PDO could not be converted to string

I thoght maybe I must make last PDO object ($db) NULL ! like this :

$db = null;
$dbh = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $db_username, $db_password);
$notification_array = $dbh -> prepare("select * from `machines`ORDER BY id DESC limit 51 ");

but by this way my code does not work and does not read table how can I create 2 simllar Pdo objects in a page ? I need it to keep them next to eachother

Answer 1

in $db = new PDO('mysql:host='.$servername.'; dbname='.$db.';charset=utf8' , $db_username, $db_password); you are using the same variable name $db for the pdo object and for the dbname You should use dbname='.$dbname for example.