mysql - How do I check if PHP is connected to a database already?

Question

Basically in pseudo code I'm looking for something like

if (connected_to_any_database()) {
    // do nothing
}
else {
    mysql_connect(...)
}

How do I implement

connected_to_any_database()

Answer 1

Have you tried mysql_ping()?

Update: From PHP 5.5 onwards, use mysqli_ping() instead.

Pings a server connection, or tries to reconnect if the connection has gone down.

if ($mysqli->ping()) {
  printf ("Our connection is ok!
"); 
} else {
  printf ("Error: %s
", $mysqli->error); 
}

Alternatively, a second (less reliable) approach would be:

$link = mysql_connect('localhost','username','password');
//(...)
if($link == false){
    //try to reconnect
}