attachments
   DB1                 |
------------------         ----------
|T1<--+--+       |<--------|        |
|     |  |       |<\     / |  DB 1' | <= connection
|     +--(---- T2|  \   /  |        |
------|--|--------   \ /   ----------
      |  |            \
------|--|--------   / \   ----------
|T1<--+--+       |  /   \  |        |
|        |       |</     \ |   DB 2'| <= connection
|        +--- T2 |<--------|        |
------------------         ----------
   DB2




MAIN   CODE:




use strict;
use Subs;
use DBI;

my $children;

for (my $i = 1; $i<=2;$i++){   ### for my $i (1..2)...  it works both ways
  my $pid = fork();
  if ($pid){
    push @children, $pid;
  }
  elsif($pid == 0){
    my $dbh = DBI->connect("dbi:SQLite:dbname=DB$i", "", "",{RaiseError=>1, AutoCommit=>1});  ## pointing to DB 1' connection and DB 2' connection
    
		
    my $joinTable = "GITAXNR";
    my $form1 = "gi INTEGER not null PRIMARY KEY, ID INTEGER not null, quest BLOB not null";
   
    
		$self->do_it_nr(argument => $beginn);
    $self->createtable_nr(table => $joinTable,
                          form => $form1);
                   
    
    $self->do_it_nr(argument => $commit); 
    for(my $j = 1; $j<=2; $j++){              ### for my $j (1..2)... it works both ways
	
      my $database = "attach database 'DBi$j' as db$j";   ## attaching DB 1 and DB 2 to DB 1' in first child or DB 2' in second child
      
      $self->do_it_nr(argument => $database); 
         
        $self->do_it_nr(argument => $beginn);   
        my $insert = "insert into GITAXNR(gi,ID,quest) select GITAX.gi, GITAX.ID, NRP.quest from db$i.GITAX inner join db$j.NRP on GITAX.gi = NRP.gi";
    	  $self->do_it_nr(argument => $insert);	  
    	  $self->do_it_nr(argument => $commit); 
    	  
    }
    
  exit;
  }
  else {
    print "could not fork:$!";
  }
}

foreach (@children){
  waitpid($_,0)
}





SUBS:


in new package:

package Subs;


##################################################
sub new {
##################################################

my ($class,%arg) = @_;


my $hash = {};

bless($hash,$class);

}




##################################################
sub do_it_nr {
##################################################
  
  my ($self, %arg) =@_;

   my $stm = $self->{argument}=$arg{argument};
  
   my $st = $dbh->prepare($stm);
   $st ->execute();               
}




##################################################
sub drop_nr {
##################################################

  my ($self,%arg) = @_;
  
  my $arg = $self->{argument}=$arg{argument};
  
    my $statement = "drop table if exists $arg";
    $self->do_it_nr(argument => $statement);            
}




##################################################
sub createtable_nr{
##################################################

  my ($self, %arg)=@_;
  
  my $form = $self->{form}=$arg{form};
  my $tabler = $self->{table}=$arg{table};

  	$self->drop_nr(argument => $tabler);
    my $stm = "create table $tabler ($form)";        
    $self->do_it_nr(argument => $stm);
}