Every database has its own way of getting a sequence number or id number from the last insert, so you are stuck with whatever your database offers in that regard. You might simplify the whole thing with something like this, though, using eval to eliminate the other conditionals (and also checks the status of getting the last id inserted, which you are not doing):

$dbh->{RaiseError}=1;
eval {
 insert...
 get last id...
 insert...
};
if ($@) {
 insert failed...
}
insert succeeded...
[download]