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(...)
}

Answer 1

// Earlier in your code
mysql_connect();
set_a_flag_that_db_is_connected();

// Later....
if (flag_is_set())
 mysql_connect(....);