Any of the above answers will suit you, but I found this solution to be useful for a similar task of mine, as it does most of the work for you:

our @connection = ($dsn, $user, $passwd, \%options);
our $dbh = DBI->connect_cached( @connection );

sub do_query {
    my = shift;
    $dbh = DBI->connect_cached( @connection );

    ## do query ##
}
[download]

connect_cached() connects if you aren't currently connected. Of course, you can do this yourself by using:

unless ($dbh->ping) {
    $dbh = DBI->connect(@connection);
}
[download]

But why?