# declare a db handle
# get a lock on the table
# call a subroutine from the module that does something to the db
# unlock the table


##</code><code>##

use dbmodule;
my $dbh;
BEGIN {$dbh = DBModule_Start}
END {DBModule_Finish}

# then do various stuff including
$sth = $dbh->prepare("BLAH BLAH") die $dbh->errstr;
$sth->execute or die $dbh->errstr;
DBModule_Sub1;


##</code><code>##

my $module_dbh;

sub
DBModule_Start
{
    unless ($module_dbh) {
       $module_dbh = DBI->connect("DBI:mysql:database=db_name", "user_name", "password");
    }
    return $module_dbh;
}

sub
DBModule_Sub1
{
    $module_dbh->do{'BLAH BLAH BLAH'} or die $module_dbh->errstr;
}

sub
DBModule_Finish
{
    $module_dbh->disconnect;
}