PHP query multiple SQL databases and return sum of results -

i'm trying create page users can enter username , have total time returned, input username issue i'll solve later i'm having trouble figuring out how execute query against 3 databases , display sum of 3 queries. i've got far, i'm aware isn't anywhere near functional know don't have clue i'm doing appreciated.

 <?php //establish database connections try {   $survivaldb = new pdo('mysql:dbname=dbname;host=ip', 'username', 'password');   $creativedb = new pdo('mysql:dbname=dbname;host=ip', 'username', 'password');   $skyblockdb = new pdo('mysql:dbname=dbname;host=ip', 'username', 'password'); } catch (pdoexception $ex) {   echo 'connection failed: ' . $ex->getmessage(); }  //query playtime on each database //survival $stmt = $survivaldb->prepare("select playtime `stats_players` `name` `:username'"); $stmt->execute(array(':username' => exampleusername)); $row = $stmt->fetch(); //creative $stmt = $creativedb->prepare("select playtime `stats_players` `name` `:username'"); $stmt->execute(array(':username' => exampleusername)); $row = $stmt->fetch(); //skyblock $stmt = $skyblockdb->prepare("select playtime `stats_players` `name` `:username'"); $stmt->execute(array(':username' => exampleusername)); $row = $stmt->fetch(); ?> 

basically end goal have text box "submit" button on site username can entered upon submission queried against databases find playtime , total returned.

thanks help!