if(!$username){
 relogin("Enter your username");
}elsif(!$password){
 relogin("Enter your password");
}

##</code><code>##

if (!$username or !$password) {
    relogin('Username/Password pair not valid');
}

##</code><code>##

my $sth = $dbh->prepare("SELECT * FROM info WHERE pword='$password'");
$sth->execute() or die "Couldnt do it: $!\n"

##</code><code>##

my $sth = $dbh->prepare('SELECT * FROM info WHERE pword=?');
$sth->execute($password) or die "Couldnt do it: $!\n"