DBI->connect() will return undef if the connection failed, so you can call first one, then another on failure by,

my $dbh = DBI->connect(@pref_args) || DBI->connect(@alt_args)
    or die $DBI::errstr;
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Your error message suggests that your connection may be failing due to bad arguments. I'm not positive of that, but it's worth checking.

The $dbh->ping method is handy for checking if a connection is still alive, once made.

You will want to avoid setting RaiseError or PrintError in the connect calls.

Actually, RaiseError defaults to 0 so you can just leave it off, but PrintError defaults to 1 so if you don't want messages printed, you'll need to explicitly set PrintError to 0 in the call to connect().

If I try to connect, and it fails, because this server is off line, my perl-script generates a message (to screen!!) that it failed. I don't want this message to screen.

Pass PrintError => 0 as an option in your connect string. From perldoc DBI:

           The "\%attr" parameter can be used to alter the
           default settings of "PrintError", "RaiseError", "Auto­
           Commit", and other attributes. For example:
 
             $dbh = DBI->connect($data_source, $user, $pass, {
                   PrintError => 0,
                   AutoCommit => 0
             });
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Update: Fixed bogus entity; added 'perldoc'.

1) are you sure the mysql server is running? try to connect using the 'mysql' command.

2) double-check your parameters, hostname, port, username and password.

3) try with a simple snippet of code.

4) if it still doesn't work, post your code here.

my $dbh = DBI->connect("DBI:mysql:database='database':host=localhost:p
+ort=3307,'root','password') or die "can't connect: $!";
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But what about: how do I know if my connection is still OK ?
Is there a command to test the connection ? or what is the best way to test this ?

Thanks
Luca

You shouldn't have to worry that much about the connection; simply test the return value of each DBI statement, if it fails, then it MAY be because the connection's lost.
$dbh->something() or .... # put your error management code here